Import upstream v0.16.22, stripped

Upstream commit: 474dd0229cb20cf513036619781ed97bd8073c3f
Enterprise-only files removed or emptied: 63
Enterprise-only snippets removed: 117 in 50 files
Dangling module declarations removed: 5
Cargo edits turning enterprise off: 14
Verification: clean
Enterprise feature gates left for rebuilt features: 19 in 18 files

Produced by tools/fork/strip.py. The full report is in docs/fork/strip-reports/ on main.

crates/smtp/Cargo.toml

@@ -0,0 +1,56 @@
+[package]
+name = "smtp"
+description = "Stalwart SMTP Server"
+authors = [ "Stalwart Labs LLC <[email protected]>"]
+repository = "https://github.com/stalwartlabs/smtp-server"
+homepage = "https://stalw.art/smtp"
+keywords = ["smtp", "email", "mail", "server"]
+categories = ["email"]
+license = "AGPL-3.0-only OR LicenseRef-SEL"
+version = "0.16.22"
+edition = "2024"
+
+[dependencies]
+store = { path =  "../store" }
+types = { path =  "../types" }
+utils = { path =  "../utils" }
+directory = { path =  "../directory" }
+common = { path =  "../common" }
+email = { path =  "../email" }
+registry = { path =  "../registry" }
+spam-filter = { path =  "../spam-filter" }
+trc = { path = "../trc" }
+mail-auth = { version = "0.13", features = ["rkyv"] }
+mail-parser = { version = "0.11", features = ["full_encoding"] } 
+mail-builder = { version = "1.0" } 
+smtp-proto = { version = "0.2.3", features = ["rkyv", "serde"] }
+sieve-rs = { version = "0.7", features = ["rkyv"] } 
+ahash = { version = "0.8" }
+rustls = { version = "0.23.43", default-features = false, features = ["std", "aws_lc_rs", "tls12"] }
+rustls-pki-types = { version = "1", features = ["std"] }
+rustls-webpki = { version = "0.103", default-features = false, features = ["std", "aws-lc-rs"] }
+tokio = { version = "1.53", features = ["full"] }
+tokio-rustls = { version = "0.26", default-features = false, features = ["aws_lc_rs", "tls12"] }
+sha2 = "0.11"
+parking_lot = "0.12"
+blake3 = "1.8"
+rand = "0.10.2"
+x509-parser = { version = "0.18", features = ["verify-aws"] }
+reqwest = { version = "0.13", default-features = false, features = ["rustls", "http2"] }
+serde = { version = "1.0", features = ["derive", "rc"] }
+serde_json = "1.0"
+rkyv = { version = "0.8.18", features = ["little_endian"] }
+compact_str = "0.10.0"
+hashify = { version = "0.2" }
+base64 = "0.23"
+
+[features]
+test_mode = ["mail-auth/test"]
+enterprise = []
+
+#[[bench]]
+#name = "hash"
+#harness = false
+
+[lints]
+workspace = true

crates/smtp/src/core/mod.rs

@@ -0,0 +1,315 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use crate::{inbound::auth::SaslToken, queue::QueueId};
+use common::{
+    Inner, Server,
+    auth::AccountInfo,
+    config::smtp::auth::VerifyStrategy,
+    network::{ServerInstance, asn::AsnGeoLookupResult},
+};
+use mail_auth::{IprevOutput, SpfOutput};
+use smtp_proto::request::receiver::{
+    BdatReceiver, DataReceiver, DummyDataReceiver, DummyLineReceiver, LineReceiver, RequestReceiver,
+};
+use std::{
+    hash::Hash,
+    net::IpAddr,
+    sync::Arc,
+    time::{Duration, Instant},
+};
+use tokio::io::{AsyncRead, AsyncWrite};
+use utils::DomainPart;
+
+pub mod params;
+pub mod throttle;
+
+#[derive(Clone)]
+pub struct SmtpSessionManager {
+    pub inner: Arc<Inner>,
+}
+
+impl SmtpSessionManager {
+    pub fn new(inner: Arc<Inner>) -> Self {
+        Self { inner }
+    }
+}
+
+pub enum State {
+    Request(RequestReceiver),
+    Bdat(BdatReceiver),
+    Data(DataReceiver),
+    Sasl(LineReceiver<SaslToken>),
+    SkipData(DummyDataReceiver, &'static [u8]),
+    RequestTooLarge(DummyLineReceiver),
+    Accepted(QueueId),
+    None,
+}
+
+pub struct Session<T: AsyncWrite + AsyncRead> {
+    pub hostname: String,
+    pub state: State,
+    pub instance: Arc<ServerInstance>,
+    pub server: Server,
+    pub stream: T,
+    pub data: SessionData,
+    pub params: SessionParameters,
+}
+
+pub struct SessionData {
+    pub session_id: u64,
+    pub local_ip: IpAddr,
+    pub local_ip_str: String,
+    pub local_port: u16,
+    pub remote_ip: IpAddr,
+    pub remote_ip_str: String,
+    pub remote_port: u16,
+    pub asn_geo_data: AsnGeoLookupResult,
+    pub helo_domain: String,
+
+    pub mail_from: Option<SessionAddress>,
+    pub rcpt_to: Vec<SessionAddress>,
+    pub rcpt_errors: usize,
+    pub rcpt_oks: usize,
+    pub message: Vec<u8>,
+
+    pub authenticated_as: Option<AccountInfo>,
+    pub auth_errors: usize,
+
+    pub priority: i16,
+    pub delivery_by: i64,
+    pub future_release: u64,
+
+    pub valid_until: Instant,
+    pub bytes_left: usize,
+    pub messages_sent: usize,
+
+    pub iprev: Option<IprevOutput>,
+    pub spf_ehlo: Option<SpfOutput>,
+    pub spf_mail_from: Option<SpfOutput>,
+    pub dnsbl_error: Option<Vec<u8>>,
+}
+
+#[derive(Clone, Debug)]
+pub struct SessionAddress {
+    pub address: String,
+    pub address_lcase: String,
+    pub domain: String,
+    pub flags: u64,
+    pub dsn_info: Option<String>,
+}
+
+#[derive(Debug, Default)]
+pub struct SessionParameters {
+    // Global parameters
+    pub timeout: Duration,
+
+    // Ehlo parameters
+    pub ehlo_require: bool,
+    pub ehlo_reject_non_fqdn: bool,
+
+    // Auth parameters
+    pub auth_require: bool,
+    pub auth_errors_max: usize,
+    pub auth_errors_wait: Duration,
+
+    // Rcpt parameters
+    pub rcpt_errors_max: usize,
+    pub rcpt_errors_wait: Duration,
+    pub rcpt_max: usize,
+    pub rcpt_dsn: bool,
+    pub can_expn: bool,
+    pub can_vrfy: bool,
+    pub max_message_size: usize,
+
+    // Mail authentication parameters
+    pub iprev: VerifyStrategy,
+    pub spf_ehlo: VerifyStrategy,
+    pub spf_mail_from: VerifyStrategy,
+}
+
+impl SessionData {
+    pub fn new(
+        local_ip: IpAddr,
+        local_port: u16,
+        remote_ip: IpAddr,
+        remote_port: u16,
+        asn_geo_data: AsnGeoLookupResult,
+        session_id: u64,
+    ) -> Self {
+        SessionData {
+            session_id,
+            local_ip,
+            local_port,
+            remote_ip,
+            local_ip_str: local_ip.to_string(),
+            remote_ip_str: remote_ip.to_string(),
+            remote_port,
+            asn_geo_data,
+            helo_domain: String::new(),
+            mail_from: None,
+            rcpt_to: Vec::new(),
+            authenticated_as: None,
+            priority: 0,
+            valid_until: Instant::now(),
+            rcpt_errors: 0,
+            rcpt_oks: 0,
+            message: Vec::with_capacity(0),
+            auth_errors: 0,
+            messages_sent: 0,
+            bytes_left: 0,
+            delivery_by: 0,
+            future_release: 0,
+            iprev: None,
+            spf_ehlo: None,
+            spf_mail_from: None,
+            dnsbl_error: None,
+        }
+    }
+}
+
+impl Default for State {
+    fn default() -> Self {
+        State::Request(RequestReceiver::default())
+    }
+}
+
+impl PartialEq for SessionAddress {
+    fn eq(&self, other: &Self) -> bool {
+        self.address_lcase == other.address_lcase
+    }
+}
+
+impl Eq for SessionAddress {}
+
+impl Hash for SessionAddress {
+    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
+        self.address_lcase.hash(state);
+    }
+}
+
+impl Ord for SessionAddress {
+    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
+        match self.domain.cmp(&other.domain) {
+            std::cmp::Ordering::Equal => self.address_lcase.cmp(&other.address_lcase),
+            order => order,
+        }
+    }
+}
+
+impl PartialOrd for SessionAddress {
+    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+impl Session<common::network::stream::NullIo> {
+    pub fn local(
+        server: Server,
+        instance: std::sync::Arc<ServerInstance>,
+        data: SessionData,
+    ) -> Self {
+        Session {
+            hostname: "localhost".into(),
+            state: State::None,
+            instance,
+            server,
+            stream: common::network::stream::NullIo::default(),
+            data,
+            params: SessionParameters {
+                timeout: Default::default(),
+                ehlo_require: Default::default(),
+                ehlo_reject_non_fqdn: Default::default(),
+                auth_require: Default::default(),
+                auth_errors_max: Default::default(),
+                auth_errors_wait: Default::default(),
+                rcpt_errors_max: Default::default(),
+                rcpt_errors_wait: Default::default(),
+                rcpt_max: Default::default(),
+                rcpt_dsn: Default::default(),
+                max_message_size: Default::default(),
+                iprev: VerifyStrategy::Disable,
+                spf_ehlo: VerifyStrategy::Disable,
+                spf_mail_from: VerifyStrategy::Disable,
+                can_expn: false,
+                can_vrfy: false,
+            },
+        }
+    }
+
+    pub fn has_failed(&mut self) -> Option<String> {
+        if self.stream.tx_buf.first().is_none_or(|&c| c == b'2') {
+            self.stream.tx_buf.clear();
+            None
+        } else {
+            let response = std::str::from_utf8(&self.stream.tx_buf)
+                .unwrap()
+                .trim()
+                .into();
+            self.stream.tx_buf.clear();
+            Some(response)
+        }
+    }
+}
+
+impl SessionData {
+    pub fn local(
+        authenticated_as: AccountInfo,
+        mail_from: Option<SessionAddress>,
+        rcpt_to: Vec<SessionAddress>,
+        message: Vec<u8>,
+        session_id: u64,
+    ) -> Self {
+        SessionData {
+            local_ip: IpAddr::V4(std::net::Ipv4Addr::new(127, 0, 0, 1)),
+            remote_ip: IpAddr::V4(std::net::Ipv4Addr::new(127, 0, 0, 1)),
+            local_ip_str: "127.0.0.1".into(),
+            remote_ip_str: "127.0.0.1".into(),
+            remote_port: 0,
+            local_port: 0,
+            session_id,
+            asn_geo_data: AsnGeoLookupResult::default(),
+            helo_domain: "localhost".into(),
+            mail_from,
+            rcpt_to,
+            rcpt_errors: 0,
+            rcpt_oks: 0,
+            message,
+            authenticated_as: Some(authenticated_as),
+            auth_errors: 0,
+            priority: 0,
+            delivery_by: 0,
+            future_release: 0,
+            valid_until: Instant::now(),
+            bytes_left: 0,
+            messages_sent: 0,
+            iprev: None,
+            spf_ehlo: None,
+            spf_mail_from: None,
+            dnsbl_error: None,
+        }
+    }
+}
+
+impl SessionAddress {
+    pub fn new(address: String) -> Self {
+        let address_lcase = address.to_lowercase();
+        SessionAddress {
+            domain: address_lcase.domain_part().into(),
+            address_lcase,
+            address,
+            flags: 0,
+            dsn_info: None,
+        }
+    }
+
+    pub fn report_address(&self) -> &str {
+        self.dsn_info
+            .as_ref()
+            .and_then(|v| v.strip_prefix("rfc822;"))
+            .unwrap_or(&self.address_lcase)
+    }
+}

crates/smtp/src/core/params.rs

@@ -0,0 +1,159 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use super::Session;
+use common::{config::smtp::auth::VerifyStrategy, network::SessionStream};
+use std::time::Duration;
+
+impl<T: SessionStream> Session<T> {
+    pub async fn eval_session_params(&mut self) {
+        let c = &self.server.core.smtp.session;
+        self.data.bytes_left = self
+            .server
+            .eval_if(&c.transfer_limit, self, self.data.session_id)
+            .await
+            .unwrap_or(250 * 1024 * 1024);
+        self.data.valid_until += self
+            .server
+            .eval_if(&c.duration, self, self.data.session_id)
+            .await
+            .unwrap_or_else(|| Duration::from_secs(15 * 60));
+
+        self.params.timeout = self
+            .server
+            .eval_if(&c.timeout, self, self.data.session_id)
+            .await
+            .unwrap_or_else(|| Duration::from_secs(5 * 60));
+        self.params.spf_ehlo = self
+            .server
+            .eval_if(
+                &self.server.core.smtp.mail_auth.spf.verify_ehlo,
+                self,
+                self.data.session_id,
+            )
+            .await
+            .unwrap_or(VerifyStrategy::Relaxed);
+        self.params.spf_mail_from = self
+            .server
+            .eval_if(
+                &self.server.core.smtp.mail_auth.spf.verify_mail_from,
+                self,
+                self.data.session_id,
+            )
+            .await
+            .unwrap_or(VerifyStrategy::Relaxed);
+        self.params.iprev = self
+            .server
+            .eval_if(
+                &self.server.core.smtp.mail_auth.iprev.verify,
+                self,
+                self.data.session_id,
+            )
+            .await
+            .unwrap_or(VerifyStrategy::Relaxed);
+
+        // Ehlo parameters
+        let ec = &self.server.core.smtp.session.ehlo;
+        self.params.ehlo_require = self
+            .server
+            .eval_if(&ec.require, self, self.data.session_id)
+            .await
+            .unwrap_or(true);
+        self.params.ehlo_reject_non_fqdn = self
+            .server
+            .eval_if(&ec.reject_non_fqdn, self, self.data.session_id)
+            .await
+            .unwrap_or(true);
+
+        // Auth parameters
+        let ac = &self.server.core.smtp.session.auth;
+        self.params.auth_require = self
+            .server
+            .eval_if(&ac.require, self, self.data.session_id)
+            .await
+            .unwrap_or(false);
+        self.params.auth_errors_max = self
+            .server
+            .eval_if(&ac.errors_max, self, self.data.session_id)
+            .await
+            .unwrap_or(3);
+        self.params.auth_errors_wait = self
+            .server
+            .eval_if(&ac.errors_wait, self, self.data.session_id)
+            .await
+            .unwrap_or_else(|| Duration::from_secs(30));
+
+        // VRFY/EXPN parameters
+        let ec = &self.server.core.smtp.session.extensions;
+        self.params.can_expn = self
+            .server
+            .eval_if(&ec.expn, self, self.data.session_id)
+            .await
+            .unwrap_or(false);
+        self.params.can_vrfy = self
+            .server
+            .eval_if(&ec.vrfy, self, self.data.session_id)
+            .await
+            .unwrap_or(false);
+    }
+
+    pub async fn eval_post_auth_params(&mut self) {
+        // Refresh VRFY/EXPN parameters
+        let ec = &self.server.core.smtp.session.extensions;
+        self.params.can_expn = self
+            .server
+            .eval_if(&ec.expn, self, self.data.session_id)
+            .await
+            .unwrap_or(false);
+        self.params.can_vrfy = self
+            .server
+            .eval_if(&ec.vrfy, self, self.data.session_id)
+            .await
+            .unwrap_or(false);
+    }
+
+    pub async fn eval_rcpt_params(&mut self) {
+        let rc = &self.server.core.smtp.session.rcpt;
+        self.params.rcpt_errors_max = self
+            .server
+            .eval_if(&rc.errors_max, self, self.data.session_id)
+            .await
+            .unwrap_or(10);
+        self.params.rcpt_errors_wait = self
+            .server
+            .eval_if(&rc.errors_wait, self, self.data.session_id)
+            .await
+            .unwrap_or_else(|| Duration::from_secs(30));
+        self.params.rcpt_max = self
+            .server
+            .eval_if(&rc.max_recipients, self, self.data.session_id)
+            .await
+            .unwrap_or(100);
+        self.params.rcpt_dsn = self
+            .server
+            .eval_if(
+                &self.server.core.smtp.session.extensions.dsn,
+                self,
+                self.data.session_id,
+            )
+            .await
+            .unwrap_or(true);
+
+        self.params.max_message_size = match self
+            .server
+            .eval_if::<usize, _>(
+                &self.server.core.smtp.session.data.max_message_size,
+                self,
+                self.data.session_id,
+            )
+            .await
+        {
+            Some(0) => usize::MAX,
+            Some(max_message_size) => max_message_size,
+            None => 25 * 1024 * 1024,
+        };
+    }
+}

crates/smtp/src/core/throttle.rs

@@ -0,0 +1,268 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use super::Session;
+use common::{
+    KV_RATE_LIMIT_SMTP, ThrottleKey, config::smtp::*, expr::functions::ResolveVariable,
+    network::SessionStream,
+};
+use queue::QueueQuota;
+use registry::schema::{enums::ExpressionVariable, structs::Rate};
+use trc::SmtpEvent;
+
+pub trait NewKey: Sized {
+    fn new_key(&self, e: &impl ResolveVariable, context: &str) -> ThrottleKey;
+}
+
+impl NewKey for QueueQuota {
+    fn new_key(&self, e: &impl ResolveVariable, _: &str) -> ThrottleKey {
+        let mut hasher = blake3::Hasher::new();
+
+        if (self.keys & THROTTLE_RCPT) != 0 {
+            hasher.update(
+                e.resolve_variable(ExpressionVariable::Rcpt)
+                    .to_string()
+                    .as_bytes(),
+            );
+        }
+        if (self.keys & THROTTLE_RCPT_DOMAIN) != 0 {
+            hasher.update(
+                e.resolve_variable(ExpressionVariable::RcptDomain)
+                    .to_string()
+                    .as_bytes(),
+            );
+        }
+        if (self.keys & THROTTLE_SENDER) != 0 {
+            let sender = e.resolve_variable(ExpressionVariable::Sender).into_string();
+            hasher.update(
+                if !sender.is_empty() {
+                    sender.as_ref()
+                } else {
+                    "<>"
+                }
+                .as_bytes(),
+            );
+        }
+        if (self.keys & THROTTLE_SENDER_DOMAIN) != 0 {
+            let sender_domain = e
+                .resolve_variable(ExpressionVariable::SenderDomain)
+                .into_string();
+            hasher.update(
+                if !sender_domain.is_empty() {
+                    sender_domain.as_ref()
+                } else {
+                    "<>"
+                }
+                .as_bytes(),
+            );
+        }
+
+        if let Some(messages) = &self.messages {
+            hasher.update(&messages.to_ne_bytes()[..]);
+        }
+
+        if let Some(size) = &self.size {
+            hasher.update(&size.to_ne_bytes()[..]);
+        }
+
+        ThrottleKey {
+            hash: hasher.finalize().into(),
+        }
+    }
+}
+
+impl NewKey for QueueRateLimiter {
+    fn new_key(&self, e: &impl ResolveVariable, context: &str) -> ThrottleKey {
+        let mut hasher = blake3::Hasher::new();
+
+        if (self.keys & THROTTLE_RCPT) != 0 {
+            hasher.update(
+                e.resolve_variable(ExpressionVariable::Rcpt)
+                    .to_string()
+                    .as_bytes(),
+            );
+        }
+        if (self.keys & THROTTLE_RCPT_DOMAIN) != 0 {
+            hasher.update(
+                e.resolve_variable(ExpressionVariable::RcptDomain)
+                    .to_string()
+                    .as_bytes(),
+            );
+        }
+        if (self.keys & THROTTLE_SENDER) != 0 {
+            let sender = e.resolve_variable(ExpressionVariable::Sender).into_string();
+            hasher.update(
+                if !sender.is_empty() {
+                    sender.as_ref()
+                } else {
+                    "<>"
+                }
+                .as_bytes(),
+            );
+        }
+        if (self.keys & THROTTLE_SENDER_DOMAIN) != 0 {
+            let sender_domain = e
+                .resolve_variable(ExpressionVariable::SenderDomain)
+                .into_string();
+            hasher.update(
+                if !sender_domain.is_empty() {
+                    sender_domain.as_ref()
+                } else {
+                    "<>"
+                }
+                .as_bytes(),
+            );
+        }
+        if (self.keys & THROTTLE_HELO_DOMAIN) != 0 {
+            hasher.update(
+                e.resolve_variable(ExpressionVariable::HeloDomain)
+                    .to_string()
+                    .as_bytes(),
+            );
+        }
+        if (self.keys & THROTTLE_AUTH_AS) != 0 {
+            hasher.update(
+                e.resolve_variable(ExpressionVariable::AuthenticatedAs)
+                    .to_string()
+                    .as_bytes(),
+            );
+        }
+        if (self.keys & THROTTLE_LISTENER) != 0 {
+            hasher.update(
+                e.resolve_variable(ExpressionVariable::Listener)
+                    .to_string()
+                    .as_bytes(),
+            );
+        }
+        if (self.keys & THROTTLE_MX) != 0 {
+            hasher.update(
+                e.resolve_variable(ExpressionVariable::Mx)
+                    .to_string()
+                    .as_bytes(),
+            );
+        }
+        if (self.keys & THROTTLE_REMOTE_IP) != 0 {
+            hasher.update(
+                e.resolve_variable(ExpressionVariable::RemoteIp)
+                    .to_string()
+                    .as_bytes(),
+            );
+        }
+        if (self.keys & THROTTLE_LOCAL_IP) != 0 {
+            hasher.update(
+                e.resolve_variable(ExpressionVariable::LocalIp)
+                    .to_string()
+                    .as_bytes(),
+            );
+        }
+        hasher.update(&self.rate.period.as_secs().to_be_bytes()[..]);
+        hasher.update(&self.rate.count.to_be_bytes()[..]);
+        hasher.update(context.as_bytes());
+
+        ThrottleKey {
+            hash: hasher.finalize().into(),
+        }
+    }
+}
+
+impl<T: SessionStream> Session<T> {
+    pub async fn is_allowed(&mut self) -> bool {
+        let throttles = if !self.data.rcpt_to.is_empty() {
+            &self.server.core.smtp.queue.inbound_limiters.rcpt
+        } else if self.data.mail_from.is_some() {
+            &self.server.core.smtp.queue.inbound_limiters.sender
+        } else {
+            &self.server.core.smtp.queue.inbound_limiters.remote
+        };
+
+        for t in throttles {
+            if t.expr.is_empty()
+                || self
+                    .server
+                    .eval_if(&t.expr, self, self.data.session_id)
+                    .await
+                    .unwrap_or(false)
+            {
+                if (t.keys & THROTTLE_RCPT_DOMAIN) != 0 {
+                    let d = self
+                        .data
+                        .rcpt_to
+                        .last()
+                        .map(|r| r.domain.as_str())
+                        .unwrap_or_default();
+
+                    if self.data.rcpt_to.iter().filter(|p| p.domain == d).count() > 1 {
+                        continue;
+                    }
+                }
+
+                // Build throttle key
+                let key = t.new_key(self, "inbound");
+
+                // Check rate
+                match self
+                    .server
+                    .in_memory_store()
+                    .is_rate_allowed(KV_RATE_LIMIT_SMTP, key.hash.as_slice(), &t.rate, false)
+                    .await
+                {
+                    Ok(Some(_)) => {
+                        trc::event!(
+                            Smtp(SmtpEvent::RateLimitExceeded),
+                            SpanId = self.data.session_id,
+                            Id = t.id.to_string(),
+                            Limit = vec![
+                                trc::Value::from(t.rate.count),
+                                trc::Value::from(t.rate.period.into_inner())
+                            ],
+                        );
+
+                        return false;
+                    }
+                    Err(err) => {
+                        trc::error!(
+                            err.span_id(self.data.session_id)
+                                .caused_by(trc::location!())
+                        );
+                    }
+                    _ => (),
+                }
+            }
+        }
+
+        true
+    }
+
+    pub async fn throttle_rcpt(&self, rcpt: &str, rate: &Rate, ctx: &str) -> bool {
+        let mut hasher = blake3::Hasher::new();
+        hasher.update(rcpt.as_bytes());
+        hasher.update(ctx.as_bytes());
+        hasher.update(&rate.period.as_secs().to_ne_bytes()[..]);
+        hasher.update(&rate.count.to_ne_bytes()[..]);
+
+        match self
+            .server
+            .in_memory_store()
+            .is_rate_allowed(
+                KV_RATE_LIMIT_SMTP,
+                hasher.finalize().as_bytes(),
+                rate,
+                false,
+            )
+            .await
+        {
+            Ok(None) => true,
+            Ok(Some(_)) => false,
+            Err(err) => {
+                trc::error!(
+                    err.span_id(self.data.session_id)
+                        .caused_by(trc::location!())
+                );
+                true
+            }
+        }
+    }
+}

crates/smtp/src/inbound/auth.rs

@@ -0,0 +1,217 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use crate::core::Session;
+use common::{auth::AuthRequest, network::SessionStream};
+use directory::Credentials;
+use mail_parser::decoders::base64::base64_decode;
+use registry::schema::enums::Permission;
+use smtp_proto::{AUTH_LOGIN, AUTH_OAUTHBEARER, AUTH_PLAIN, AUTH_XOAUTH2, IntoString};
+use trc::AuthEvent;
+
+pub struct SaslToken {
+    mechanism: u64,
+    credentials: Credentials,
+}
+
+impl SaslToken {
+    pub fn from_mechanism(mechanism: u64) -> Option<SaslToken> {
+        match mechanism {
+            AUTH_PLAIN | AUTH_LOGIN => SaslToken {
+                mechanism,
+                credentials: Credentials::Basic {
+                    username: String::new(),
+                    secret: String::new(),
+                    mfa_token: None,
+                },
+            }
+            .into(),
+            AUTH_OAUTHBEARER | AUTH_XOAUTH2 => SaslToken {
+                mechanism,
+                credentials: Credentials::Bearer {
+                    username: None,
+                    token: String::new(),
+                },
+            }
+            .into(),
+            _ => None,
+        }
+    }
+}
+
+impl<T: SessionStream> Session<T> {
+    pub async fn handle_sasl_response(
+        &mut self,
+        token: &mut SaslToken,
+        response: &[u8],
+    ) -> Result<bool, ()> {
+        if response.is_empty() {
+            match (token.mechanism, &token.credentials) {
+                (AUTH_PLAIN | AUTH_XOAUTH2 | AUTH_OAUTHBEARER, _) => {
+                    self.write(b"334 \r\n").await?;
+                    return Ok(true);
+                }
+                (
+                    AUTH_LOGIN,
+                    Credentials::Basic {
+                        username, secret, ..
+                    },
+                ) if username.is_empty() && secret.is_empty() => {
+                    self.write(b"334 VXNlcm5hbWU6\r\n").await?;
+                    return Ok(true);
+                }
+                _ => (),
+            }
+        } else if let Some(response) = base64_decode(response) {
+            match (token.mechanism, &mut token.credentials) {
+                (AUTH_PLAIN, _) => {
+                    if let Some(credentials) = Credentials::decode_sasl_challenge_plain(&response) {
+                        return self.authenticate(credentials).await;
+                    }
+                }
+                (
+                    AUTH_LOGIN,
+                    Credentials::Basic {
+                        username, secret, ..
+                    },
+                ) => {
+                    return if username.is_empty() {
+                        *username = response.into_string();
+                        self.write(b"334 UGFzc3dvcmQ6\r\n").await?;
+                        Ok(true)
+                    } else {
+                        *secret = response.into_string();
+                        self.authenticate(std::mem::replace(
+                            &mut token.credentials,
+                            Credentials::Basic {
+                                username: String::new(),
+                                secret: String::new(),
+                                mfa_token: None,
+                            },
+                        ))
+                        .await
+                    };
+                }
+                (AUTH_OAUTHBEARER | AUTH_XOAUTH2, _) => {
+                    if let Some(credentials) = Credentials::decode_sasl_challenge_oauth(&response) {
+                        return self.authenticate(credentials).await;
+                    }
+                }
+                _ => (),
+            }
+        }
+
+        self.auth_error(b"500 5.5.6 Invalid challenge.\r\n").await
+    }
+
+    pub async fn authenticate(&mut self, credentials: Credentials) -> Result<bool, ()> {
+        // Authenticate
+        let result = self
+            .server
+            .authenticate(&AuthRequest::from_credentials(
+                credentials,
+                self.data.session_id,
+                self.data.remote_ip,
+            ))
+            .await
+            .and_then(|access_token| access_token.assert_has_permission(Permission::EmailSend));
+
+        let result = match result {
+            Ok(access_token) => self.server.account_info(access_token.account_id()).await,
+            Err(err) => Err(err),
+        };
+
+        match result {
+            Ok(account_info) => {
+                self.data.authenticated_as = account_info.into();
+                self.eval_post_auth_params().await;
+                self.write(b"235 2.7.0 Authentication succeeded.\r\n")
+                    .await?;
+                return Ok(false);
+            }
+            Err(err) => {
+                let reason = *err.as_ref();
+
+                trc::error!(err.span_id(self.data.session_id));
+
+                match reason {
+                    trc::EventType::Auth(trc::AuthEvent::Failed) => {
+                        return self
+                            .auth_error(b"535 5.7.8 Authentication credentials invalid.\r\n")
+                            .await;
+                    }
+                    trc::EventType::Auth(trc::AuthEvent::TokenExpired) => {
+                        return self.auth_error(b"535 5.7.8 OAuth token expired.\r\n").await;
+                    }
+                    trc::EventType::Auth(trc::AuthEvent::MfaRequired) => {
+                        return self
+                            .auth_error(
+                                concat!(
+                                    "334 5.7.8 This account requires multi-factor authentication. ",
+                                    "Alternatively, you can use an app password if your account has one.\r\n"
+                                )
+                                .as_bytes(),
+                            )
+                            .await;
+                    }
+                    trc::EventType::Security(trc::SecurityEvent::Unauthorized) => {
+                        self.write(
+                            concat!(
+                                "550 5.7.1 Your account is not authorized ",
+                                "to use this service.\r\n"
+                            )
+                            .as_bytes(),
+                        )
+                        .await?;
+                        return Ok(false);
+                    }
+                    trc::EventType::Security(_) => {
+                        return Err(());
+                    }
+                    _ => (),
+                }
+            }
+        }
+
+        self.write(b"454 4.7.0 Temporary authentication failure\r\n")
+            .await?;
+
+        Ok(false)
+    }
+
+    pub async fn auth_error(&mut self, response: &[u8]) -> Result<bool, ()> {
+        tokio::time::sleep(self.params.auth_errors_wait).await;
+        self.data.auth_errors += 1;
+        self.write(response).await?;
+        if self.data.auth_errors < self.params.auth_errors_max {
+            Ok(false)
+        } else {
+            trc::event!(
+                Auth(AuthEvent::TooManyAttempts),
+                SpanId = self.data.session_id,
+            );
+
+            self.write(b"455 4.3.0 Too many authentication errors, disconnecting.\r\n")
+                .await?;
+            Err(())
+        }
+    }
+
+    pub fn authenticated_as(&self) -> Option<&str> {
+        self.data
+            .authenticated_as
+            .as_ref()
+            .map(|authenticated_as| authenticated_as.name())
+    }
+
+    pub fn is_authenticated(&self) -> bool {
+        self.data.authenticated_as.is_some()
+    }
+
+    pub fn authenticated_emails(&self) -> &[String] {
+        self.data.authenticated_as.as_ref().unwrap().addresses()
+    }
+}

crates/smtp/src/inbound/dkim.rs

@@ -0,0 +1,418 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use crate::queue::{MessageWrapper, Metadata, spool::QueueParams};
+use common::{
+    Server,
+    config::smtp::auth::{Dkim1Signer, DkimSigners},
+    expr::{functions::ResolveVariable, if_block::IfBlock},
+};
+use mail_auth::{
+    AuthenticatedMessage,
+    common::headers::HeaderWriter,
+    dkim2::{Hop, MessageInstance},
+};
+use mail_parser::{Address, parsers::MessageStream};
+use std::{collections::HashSet, sync::Arc};
+use utils::sanitize_email;
+
+pub(crate) trait DkimSign: Sync + Send {
+    fn sign_message(
+        &self,
+        message: &mut MessageWrapper,
+        params: &mut QueueParams<'_, '_>,
+    ) -> impl Future<Output = Option<Vec<u8>>> + Send;
+
+    fn eval_signers(
+        &self,
+        if_block: &IfBlock,
+        resolver: &impl ResolveVariable,
+        session_id: u64,
+    ) -> impl Future<Output = Option<Arc<DkimSigners>>> + Send;
+}
+
+impl DkimSign for Server {
+    async fn sign_message(
+        &self,
+        message: &mut MessageWrapper,
+        params: &mut QueueParams<'_, '_>,
+    ) -> Option<Vec<u8>> {
+        let signers = params.dkim_signers.as_ref().unwrap();
+        let raw_message = params.raw_message;
+
+        // DKIM1 signing
+        let mut headers = Vec::with_capacity(64);
+        for signer in &signers.dkim1 {
+            let result = match (signer, params.raw_headers) {
+                (Dkim1Signer::RsaSha256(signer), None) => signer.sign(raw_message),
+                (Dkim1Signer::Ed25519Sha256(signer), None) => signer.sign(raw_message),
+                (Dkim1Signer::RsaSha256(signer), Some(headers)) => {
+                    signer.sign_chained([headers, raw_message].iter().copied())
+                }
+                (Dkim1Signer::Ed25519Sha256(signer), Some(headers)) => {
+                    signer.sign_chained([headers, raw_message].iter().copied())
+                }
+            };
+
+            match result {
+                Ok(signature) => {
+                    signature.write_header(&mut headers);
+                }
+                Err(err) => {
+                    trc::error!(
+                        trc::Error::from(err)
+                            .span_id(params.session_id)
+                            .details("Failed to sign message")
+                            .caused_by(trc::location!())
+                    );
+                }
+            }
+        }
+
+        // DKIM2 signing
+        if let Some(signer) = &signers.dkim2
+            && let Some(modified) =
+                AuthenticatedMessage::parse_with_opts(raw_message, params.raw_headers, true)
+        {
+            // Generate message instance
+            let original = params.original_authenticated_message.take().or_else(|| {
+                params
+                    .original_raw_message
+                    .and_then(AuthenticatedMessage::parse)
+            });
+            let instance = MessageInstance::from_message(&modified, original.as_ref());
+            if let Some(instance) = &instance {
+                instance.write_header(&mut headers);
+            }
+
+            // Obtain disclosed and undisclosed recipients
+            let envelopes = message.undisclosed_recipients(&modified);
+
+            // Generate DKIM2 signature for disclosed recipients
+            if !envelopes.disclosed_recipients.is_empty() {
+                match signer.sign_with_message_instance(
+                    &modified,
+                    instance.as_ref(),
+                    Hop::real(
+                        message.message.return_path.as_ref(),
+                        envelopes.disclosed_recipients,
+                    ),
+                ) {
+                    Ok(signature) => {
+                        if envelopes.undisclosed_recipients.is_empty() {
+                            // Happy path: no undisclosed recipients, serialize signature straight to blob
+                            signature.write_header(&mut headers);
+                        } else {
+                            // Undisclosed recipients present, serialize signature to metadata
+                            let mut header = Vec::with_capacity(64);
+                            signature.write_header(&mut header);
+                            params.metadata.push(Metadata::Headers {
+                                value: header.into_boxed_slice(),
+                                id: u64::MAX,
+                            });
+                        }
+                    }
+                    Err(err) => {
+                        trc::error!(
+                            trc::Error::from(err)
+                                .span_id(params.session_id)
+                                .details("Failed to DKIM2 sign message")
+                        );
+                    }
+                }
+            }
+
+            // Generate DKIM2 signature for undisclosed recipients
+            for (pos, rcpt) in envelopes.undisclosed_recipients {
+                match signer.sign_with_message_instance(
+                    &modified,
+                    instance.as_ref(),
+                    Hop::real(message.message.return_path.as_ref(), [rcpt]),
+                ) {
+                    Ok(signature) => {
+                        // Serialize signature to metadata
+                        let mut header = Vec::with_capacity(64);
+                        signature.write_header(&mut header);
+                        params.metadata.push(Metadata::Headers {
+                            value: header.into_boxed_slice(),
+                            id: pos as u64,
+                        });
+                    }
+                    Err(err) => {
+                        trc::error!(
+                            trc::Error::from(err)
+                                .span_id(params.session_id)
+                                .details("Failed to DKIM2 sign message")
+                        );
+                    }
+                }
+            }
+        }
+
+        (!headers.is_empty()).then_some(headers)
+    }
+
+    async fn eval_signers(
+        &self,
+        if_block: &IfBlock,
+        resolver: &impl ResolveVariable,
+        session_id: u64,
+    ) -> Option<Arc<DkimSigners>> {
+        let sign_with_domain = self
+            .eval_if::<String, _>(if_block, resolver, session_id)
+            .await?;
+        match self.dkim_signers(&sign_with_domain).await {
+            Ok(signers) => signers,
+            Err(err) => {
+                trc::error!(
+                    err.span_id(session_id)
+                        .details("Failed to retrieve DKIM signers")
+                );
+                None
+            }
+        }
+    }
+}
+
+struct Dkim2Envelopes<'x> {
+    undisclosed_recipients: Vec<(usize, &'x str)>,
+    disclosed_recipients: Vec<&'x str>,
+}
+
+impl MessageWrapper {
+    fn undisclosed_recipients<'x>(
+        &'x self,
+        message: &AuthenticatedMessage<'_>,
+    ) -> Dkim2Envelopes<'x> {
+        if self.message.recipients.len() == 1 {
+            return Dkim2Envelopes {
+                undisclosed_recipients: Vec::new(),
+                disclosed_recipients: vec![self.message.recipients[0].address.as_ref()],
+            };
+        }
+
+        let mut recipients = HashSet::with_capacity(self.message.recipients.len());
+
+        for addr in message.headers.iter().filter_map(|(name, value)| {
+            let name = name.trim_ascii();
+            if name.len() == 2
+                && (name.eq_ignore_ascii_case(b"to") || name.eq_ignore_ascii_case(b"cc"))
+            {
+                MessageStream::new(value).parse_address().into_address()
+            } else {
+                None
+            }
+        }) {
+            match addr {
+                Address::List(addrs) => {
+                    recipients.extend(
+                        addrs
+                            .iter()
+                            .filter_map(|a| a.address())
+                            .map(sanitize_or_lower),
+                    );
+                }
+                Address::Group(groups) => {
+                    for group in groups {
+                        recipients.extend(
+                            group
+                                .addresses
+                                .iter()
+                                .filter_map(|a| a.address())
+                                .map(sanitize_or_lower),
+                        );
+                    }
+                }
+            }
+        }
+
+        let mut undisclosed_recipients = Vec::new();
+        let mut disclosed_recipients = Vec::new();
+        for (i, rcpt) in self.message.recipients.iter().enumerate() {
+            if !recipients.contains(rcpt.address.as_ref())
+                && !recipients.contains(&sanitize_or_lower(&rcpt.address))
+            {
+                undisclosed_recipients.push((i, rcpt.address.as_ref()));
+            } else {
+                disclosed_recipients.push(rcpt.address.as_ref());
+            }
+        }
+
+        Dkim2Envelopes {
+            undisclosed_recipients,
+            disclosed_recipients,
+        }
+    }
+}
+
+fn sanitize_or_lower(rcpt: &str) -> String {
+    sanitize_email(rcpt).unwrap_or_else(|| rcpt.to_lowercase())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::queue::{Message, QueueId, Recipient};
+    use common::config::smtp::queue::QueueName;
+    use std::net::{IpAddr, Ipv4Addr};
+
+    fn wrapper(recipients: &[&str]) -> MessageWrapper {
+        MessageWrapper {
+            queue_id: 0 as QueueId,
+            queue_name: QueueName::default(),
+            is_multi_queue: false,
+            span_id: 0,
+            message: Message {
+                created: 0,
+                blob_hash: Default::default(),
+                return_path: "[email protected]".into(),
+                recipients: recipients.iter().map(Recipient::new).collect(),
+                received_from_ip: IpAddr::V4(Ipv4Addr::LOCALHOST),
+                received_via_port: 0,
+                flags: 0,
+                env_id: None,
+                priority: 0,
+                size: 0,
+                metadata: Default::default(),
+            },
+        }
+    }
+
+    fn split(headers: &str, recipients: &[&str]) -> (Vec<String>, Vec<String>) {
+        let raw = format!("{headers}\r\nSubject: test\r\n\r\nbody\r\n");
+        let auth = AuthenticatedMessage::parse(raw.as_bytes()).expect("parse message");
+        let message = wrapper(recipients);
+        let envelopes = message.undisclosed_recipients(&auth);
+        let mut disclosed = envelopes
+            .disclosed_recipients
+            .iter()
+            .map(|s| s.to_string())
+            .collect::<Vec<_>>();
+        let mut undisclosed = envelopes
+            .undisclosed_recipients
+            .iter()
+            .map(|(_, s)| s.to_string())
+            .collect::<Vec<_>>();
+        disclosed.sort();
+        undisclosed.sort();
+        (disclosed, undisclosed)
+    }
+
+    #[test]
+    fn single_recipient_is_always_disclosed() {
+        let (disclosed, undisclosed) = split("To: [email protected]", &["[email protected]"]);
+        assert_eq!(disclosed, vec!["[email protected]".to_string()]);
+        assert!(undisclosed.is_empty());
+    }
+
+    #[test]
+    fn all_recipients_disclosed() {
+        let (disclosed, undisclosed) = split(
+            "To: [email protected], [email protected]\r\nCc: [email protected]",
+            &["[email protected]", "[email protected]", "[email protected]"],
+        );
+        assert_eq!(
+            disclosed,
+            vec![
+                "[email protected]".to_string(),
+                "[email protected]".to_string(),
+                "[email protected]".to_string(),
+            ]
+        );
+        assert!(undisclosed.is_empty());
+    }
+
+    #[test]
+    fn mixed_disclosed_and_undisclosed() {
+        let (disclosed, undisclosed) = split(
+            "To: [email protected]\r\nCc: [email protected]",
+            &[
+                "[email protected]",
+                "[email protected]",
+                "[email protected]",
+                "[email protected]",
+            ],
+        );
+        assert_eq!(
+            disclosed,
+            vec![
+                "[email protected]".to_string(),
+                "[email protected]".to_string()
+            ]
+        );
+        assert_eq!(
+            undisclosed,
+            vec![
+                "[email protected]".to_string(),
+                "[email protected]".to_string(),
+            ]
+        );
+    }
+
+    #[test]
+    fn no_to_or_cc_header_all_undisclosed() {
+        let (disclosed, undisclosed) = split(
+            "From: [email protected]",
+            &["[email protected]", "[email protected]"],
+        );
+        assert!(disclosed.is_empty());
+        assert_eq!(
+            undisclosed,
+            vec![
+                "[email protected]".to_string(),
+                "[email protected]".to_string()
+            ]
+        );
+    }
+
+    #[test]
+    fn group_addresses_are_disclosed() {
+        let (disclosed, undisclosed) = split(
+            "To: Team:[email protected],[email protected];",
+            &["[email protected]", "[email protected]", "[email protected]"],
+        );
+        assert_eq!(
+            disclosed,
+            vec![
+                "[email protected]".to_string(),
+                "[email protected]".to_string()
+            ]
+        );
+        assert_eq!(undisclosed, vec!["[email protected]".to_string()]);
+    }
+
+    #[test]
+    fn header_address_casing_is_ignored() {
+        let (disclosed, undisclosed) = split(
+            "To: [email protected], [email protected]",
+            &["[email protected]", "[email protected]", "[email protected]"],
+        );
+        assert_eq!(
+            disclosed,
+            vec![
+                "[email protected]".to_string(),
+                "[email protected]".to_string()
+            ]
+        );
+        assert_eq!(undisclosed, vec!["[email protected]".to_string()]);
+    }
+
+    #[test]
+    fn display_names_and_brackets_are_ignored() {
+        let (disclosed, undisclosed) = split(
+            "To: \"Alice Doe\" <[email protected]>\r\nCc: Bob <[email protected]>",
+            &["[email protected]", "[email protected]", "[email protected]"],
+        );
+        assert_eq!(
+            disclosed,
+            vec![
+                "[email protected]".to_string(),
+                "[email protected]".to_string()
+            ]
+        );
+        assert_eq!(undisclosed, vec!["[email protected]".to_string()]);
+    }
+}

crates/smtp/src/inbound/ehlo.rs

@@ -0,0 +1,292 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use crate::{core::Session, scripts::ScriptResult};
+use common::{
+    config::smtp::session::{Mechanism, Stage},
+    network::SessionStream,
+};
+use mail_auth::{
+    SpfResult,
+    spf::verify::{HasValidLabels, SpfParameters},
+};
+use smtp_proto::*;
+use std::{
+    borrow::Cow,
+    time::{Duration, Instant, SystemTime},
+};
+use trc::SmtpEvent;
+
+impl<T: SessionStream> Session<T> {
+    pub async fn handle_ehlo(&mut self, domain: Cow<'_, str>, is_extended: bool) -> Result<(), ()> {
+        // Set EHLO domain
+
+        if domain != self.data.helo_domain {
+            // Reject non-FQDN EHLO domains - simply checks that the hostname has at least one dot
+            if self.params.ehlo_reject_non_fqdn && !domain.as_ref().has_valid_labels() {
+                trc::event!(
+                    Smtp(SmtpEvent::InvalidEhlo),
+                    SpanId = self.data.session_id,
+                    Domain = domain.as_ref().to_string(),
+                );
+
+                return self.write(b"550 5.5.0 Invalid EHLO domain.\r\n").await;
+            }
+
+            trc::event!(
+                Smtp(SmtpEvent::Ehlo),
+                SpanId = self.data.session_id,
+                Domain = domain.as_ref().to_string(),
+            );
+
+            // SPF check
+            let prev_helo_domain =
+                std::mem::replace(&mut self.data.helo_domain, domain.into_owned());
+            if self.params.spf_ehlo.verify() {
+                let time = Instant::now();
+                let spf_output = self
+                    .server
+                    .core
+                    .smtp
+                    .resolvers
+                    .dns
+                    .verify_spf(self.server.inner.cache.build_auth_parameters(
+                        SpfParameters::verify_ehlo(
+                            self.data.remote_ip,
+                            &self.data.helo_domain,
+                            &self.hostname,
+                        ),
+                    ))
+                    .await;
+
+                trc::event!(
+                    Smtp(if matches!(spf_output.result(), SpfResult::Pass) {
+                        SmtpEvent::SpfEhloPass
+                    } else {
+                        SmtpEvent::SpfEhloFail
+                    }),
+                    SpanId = self.data.session_id,
+                    Domain = self.data.helo_domain.clone(),
+                    Result = trc::Error::from(&spf_output),
+                    Elapsed = time.elapsed(),
+                );
+
+                if self
+                    .handle_spf(&spf_output, self.params.spf_ehlo.is_strict())
+                    .await?
+                {
+                    self.data.spf_ehlo = spf_output.into();
+                } else {
+                    self.data.mail_from = None;
+                    self.data.helo_domain = prev_helo_domain;
+                    return Ok(());
+                }
+            }
+
+            // Sieve filtering
+            if let Some((script, script_id)) = self
+                .server
+                .eval_if::<String, _>(
+                    &self.server.core.smtp.session.ehlo.script,
+                    self,
+                    self.data.session_id,
+                )
+                .await
+                .and_then(|name| {
+                    self.server
+                        .get_trusted_sieve_script(&name, self.data.session_id)
+                        .map(|s| (s, name))
+                })
+                && let ScriptResult::Reject(message) = self
+                    .run_script(
+                        script_id,
+                        script.clone(),
+                        self.build_script_parameters("ehlo"),
+                    )
+                    .await
+            {
+                self.data.mail_from = None;
+                self.data.helo_domain = prev_helo_domain;
+                self.data.spf_ehlo = None;
+                return self.write(message.as_bytes()).await;
+            }
+
+            // Milter filtering
+            if let Err(message) = self.run_milters(Stage::Ehlo, None, None).await {
+                self.data.mail_from = None;
+                self.data.helo_domain = prev_helo_domain;
+                self.data.spf_ehlo = None;
+                return self.write(message.message.as_bytes()).await;
+            }
+
+            // MTAHook filtering
+            if let Err(message) = self.run_mta_hooks(Stage::Ehlo, None, None).await {
+                self.data.mail_from = None;
+                self.data.helo_domain = prev_helo_domain;
+                self.data.spf_ehlo = None;
+                return self.write(message.message.as_bytes()).await;
+            }
+        }
+
+        // Reset
+        if self.data.mail_from.is_some() {
+            self.reset();
+        }
+
+        if !is_extended {
+            return self
+                .write(format!("250 {} you had me at HELO\r\n", self.hostname).as_bytes())
+                .await;
+        }
+
+        let mut response = EhloResponse::new(self.hostname.as_str());
+        response.capabilities =
+            EXT_ENHANCED_STATUS_CODES | EXT_8BIT_MIME | EXT_BINARY_MIME | EXT_SMTP_UTF8;
+        if !self.stream.is_tls() && self.instance.acceptor.is_tls() {
+            response.capabilities |= EXT_START_TLS;
+        }
+        let ec = &self.server.core.smtp.session.extensions;
+        let ac = &self.server.core.smtp.session.auth;
+        let dc = &self.server.core.smtp.session.data;
+
+        // Pipelining
+        if self
+            .server
+            .eval_if(&ec.pipelining, self, self.data.session_id)
+            .await
+            .unwrap_or(true)
+        {
+            response.capabilities |= EXT_PIPELINING;
+        }
+
+        // Chunking
+        if self
+            .server
+            .eval_if(&ec.chunking, self, self.data.session_id)
+            .await
+            .unwrap_or(true)
+        {
+            response.capabilities |= EXT_CHUNKING;
+        }
+
+        // Address Expansion
+        if self
+            .server
+            .eval_if(&ec.expn, self, self.data.session_id)
+            .await
+            .unwrap_or(false)
+        {
+            response.capabilities |= EXT_EXPN;
+        }
+
+        // Recipient Verification
+        if self
+            .server
+            .eval_if(&ec.vrfy, self, self.data.session_id)
+            .await
+            .unwrap_or(false)
+        {
+            response.capabilities |= EXT_VRFY;
+        }
+
+        // Require TLS
+        if self
+            .server
+            .eval_if(&ec.requiretls, self, self.data.session_id)
+            .await
+            .unwrap_or(true)
+        {
+            response.capabilities |= EXT_REQUIRE_TLS;
+        }
+
+        // DSN
+        if self
+            .server
+            .eval_if(&ec.dsn, self, self.data.session_id)
+            .await
+            .unwrap_or(false)
+        {
+            response.capabilities |= EXT_DSN;
+        }
+
+        // Authentication
+        if !self.is_authenticated() {
+            response.auth_mechanisms = self
+                .server
+                .eval_if::<Mechanism, _>(&ac.mechanisms, self, self.data.session_id)
+                .await
+                .unwrap_or_default()
+                .into();
+            if response.auth_mechanisms != 0 {
+                response.capabilities |= EXT_AUTH;
+            }
+        }
+
+        // Future release
+        if let Some(value) = self
+            .server
+            .eval_if::<Duration, _>(&ec.future_release, self, self.data.session_id)
+            .await
+        {
+            response.capabilities |= EXT_FUTURE_RELEASE;
+            response.future_release_interval = value.as_secs();
+            response.future_release_datetime = SystemTime::now()
+                .duration_since(SystemTime::UNIX_EPOCH)
+                .map(|d| d.as_secs())
+                .unwrap_or(0)
+                + value.as_secs();
+        }
+
+        // Deliver By
+        if let Some(value) = self
+            .server
+            .eval_if::<Duration, _>(&ec.deliver_by, self, self.data.session_id)
+            .await
+        {
+            response.capabilities |= EXT_DELIVER_BY;
+            response.deliver_by = value.as_secs();
+        }
+
+        // Priority
+        if let Some(value) = self
+            .server
+            .eval_if::<MtPriority, _>(&ec.mt_priority, self, self.data.session_id)
+            .await
+        {
+            response.capabilities |= EXT_MT_PRIORITY;
+            response.mt_priority = value;
+        }
+
+        // Size
+        response.size = self
+            .server
+            .eval_if(&dc.max_message_size, self, self.data.session_id)
+            .await
+            .unwrap_or(25 * 1024 * 1024);
+        if response.size > 0 {
+            response.capabilities |= EXT_SIZE;
+        }
+
+        // No soliciting
+        if let Some(value) = self
+            .server
+            .eval_if::<String, _>(&ec.no_soliciting, self, self.data.session_id)
+            .await
+        {
+            response.capabilities |= EXT_NO_SOLICITING;
+            response.no_soliciting = if !value.is_empty() {
+                value.to_string().into()
+            } else {
+                None
+            };
+        }
+
+        // Generate response
+        let mut buf = Vec::with_capacity(64);
+        response.write(&mut buf).ok();
+        self.write(&buf).await
+    }
+}

crates/smtp/src/inbound/hooks/client.rs

@@ -0,0 +1,46 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use common::config::smtp::session::MTAHook;
+use utils::HttpLimitResponse;
+
+use super::{Request, Response};
+
+pub(super) async fn send_mta_hook_request(
+    mta_hook: &MTAHook,
+    request: Request,
+) -> Result<Response, String> {
+    let response = mta_hook
+        .client
+        .post(&mta_hook.url)
+        .timeout(mta_hook.timeout)
+        .headers(mta_hook.headers.clone())
+        .body(
+            serde_json::to_string(&request)
+                .map_err(|err| format!("Failed to serialize Hook request: {}", err))?,
+        )
+        .send()
+        .await
+        .map_err(|err| format!("Hook request failed: {err}"))?;
+
+    if response.status().is_success() {
+        serde_json::from_slice(
+            response
+                .bytes_with_limit(mta_hook.max_response_size)
+                .await
+                .map_err(|err| format!("Failed to parse Hook response: {}", err))?
+                .ok_or_else(|| "Hook response too large".to_string())?
+                .as_ref(),
+        )
+        .map_err(|err| format!("Failed to parse Hook response: {}", err))
+    } else {
+        Err(format!(
+            "Hook request failed with code {}: {}",
+            response.status().as_u16(),
+            response.status().canonical_reason().unwrap_or("Unknown")
+        ))
+    }
+}

crates/smtp/src/inbound/hooks/message.rs

@@ -0,0 +1,268 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use super::{Action, Queue, Response, client::send_mta_hook_request};
+use crate::{
+    core::Session,
+    inbound::{
+        FilterResponse,
+        hooks::{
+            Address, Client, Context, Envelope, Message, Protocol, Request, Sasl, Server, Tls,
+        },
+        milter::Modification,
+    },
+    queue::QueueId,
+};
+use ahash::AHashMap;
+use common::{
+    DAEMON_NAME,
+    config::smtp::session::{MTAHook, Stage},
+    network::SessionStream,
+};
+use mail_auth::AuthenticatedMessage;
+use std::time::Instant;
+use trc::MtaHookEvent;
+
+impl<T: SessionStream> Session<T> {
+    pub async fn run_mta_hooks(
+        &self,
+        stage: Stage,
+        message: Option<&AuthenticatedMessage<'_>>,
+        queue_id: Option<QueueId>,
+    ) -> Result<Vec<Modification>, FilterResponse> {
+        let mta_hooks = &self.server.core.smtp.session.hooks;
+        if mta_hooks.is_empty() {
+            return Ok(Vec::new());
+        }
+
+        let mut modifications = Vec::new();
+        for mta_hook in mta_hooks {
+            if !mta_hook.run_on_stage.contains(&stage)
+                || !self
+                    .server
+                    .eval_if(&mta_hook.enable, self, self.data.session_id)
+                    .await
+                    .unwrap_or(false)
+            {
+                continue;
+            }
+
+            let time = Instant::now();
+            match self.run_mta_hook(stage, mta_hook, message, queue_id).await {
+                Ok(response) => {
+                    trc::event!(
+                        MtaHook(match response.action {
+                            Action::Accept => MtaHookEvent::ActionAccept,
+                            Action::Discard => MtaHookEvent::ActionDiscard,
+                            Action::Reject => MtaHookEvent::ActionReject,
+                            Action::Quarantine => MtaHookEvent::ActionQuarantine,
+                        }),
+                        SpanId = self.data.session_id,
+                        QueueId = queue_id,
+                        Id = mta_hook.id.to_string(),
+                        Elapsed = time.elapsed(),
+                    );
+
+                    let mut new_modifications = Vec::with_capacity(response.modifications.len());
+                    for modification in response.modifications {
+                        new_modifications.push(match modification {
+                            super::Modification::ChangeFrom { value, parameters } => {
+                                Modification::ChangeFrom {
+                                    sender: value,
+                                    args: flatten_parameters(parameters),
+                                }
+                            }
+                            super::Modification::AddRecipient { value, parameters } => {
+                                Modification::AddRcpt {
+                                    recipient: value,
+                                    args: flatten_parameters(parameters),
+                                }
+                            }
+                            super::Modification::DeleteRecipient { value } => {
+                                Modification::DeleteRcpt { recipient: value }
+                            }
+                            super::Modification::ReplaceContents { value } => {
+                                Modification::ReplaceBody {
+                                    value: value.as_bytes().to_vec(),
+                                }
+                            }
+                            super::Modification::AddHeader { name, value } => {
+                                Modification::AddHeader { name, value }
+                            }
+                            super::Modification::InsertHeader { index, name, value } => {
+                                Modification::InsertHeader { index, name, value }
+                            }
+                            super::Modification::ChangeHeader { index, name, value } => {
+                                Modification::ChangeHeader { index, name, value }
+                            }
+                            super::Modification::DeleteHeader { index, name } => {
+                                Modification::ChangeHeader {
+                                    index,
+                                    name,
+                                    value: String::new(),
+                                }
+                            }
+                        });
+                    }
+
+                    if !modifications.is_empty() {
+                        // The message body can only be replaced once, so we need to remove
+                        // any previous replacements.
+                        if new_modifications
+                            .iter()
+                            .any(|m| matches!(m, Modification::ReplaceBody { .. }))
+                        {
+                            modifications
+                                .retain(|m| !matches!(m, Modification::ReplaceBody { .. }));
+                        }
+                        modifications.extend(new_modifications);
+                    } else {
+                        modifications = new_modifications;
+                    }
+
+                    let mut message = match response.action {
+                        Action::Accept => continue,
+                        Action::Discard => FilterResponse::accept(),
+                        Action::Reject => FilterResponse::reject(),
+                        Action::Quarantine => {
+                            modifications.push(Modification::AddHeader {
+                                name: "X-Quarantine".into(),
+                                value: "true".into(),
+                            });
+                            FilterResponse::accept()
+                        }
+                    };
+
+                    if let Some(response) = response.response {
+                        if let (Some(status), Some(text)) = (response.status, response.message) {
+                            if let Some(enhanced) = response.enhanced_status {
+                                message.message = format!("{status} {enhanced} {text}\r\n").into();
+                            } else {
+                                message.message = format!("{status} {text}\r\n").into();
+                            }
+                        }
+                        message.disconnect = response.disconnect;
+                    }
+
+                    return Err(message);
+                }
+                Err(err) => {
+                    trc::event!(
+                        MtaHook(MtaHookEvent::Error),
+                        SpanId = self.data.session_id,
+                        Id = mta_hook.id.to_string(),
+                        Reason = err,
+                        Elapsed = time.elapsed(),
+                    );
+
+                    if mta_hook.tempfail_on_error {
+                        return Err(FilterResponse::server_failure());
+                    }
+                }
+            }
+        }
+
+        Ok(modifications)
+    }
+
+    pub async fn run_mta_hook(
+        &self,
+        stage: Stage,
+        mta_hook: &MTAHook,
+        message: Option<&AuthenticatedMessage<'_>>,
+        queue_id: Option<QueueId>,
+    ) -> Result<Response, String> {
+        // Build request
+        let (tls_version, tls_cipher) = self.stream.tls_version_and_cipher();
+        let request = Request {
+            context: Context {
+                stage: stage.into(),
+                client: Client {
+                    ip: self.data.remote_ip.to_string(),
+                    port: self.data.remote_port,
+                    ptr: self
+                        .data
+                        .iprev
+                        .as_ref()
+                        .and_then(|ip_rev| ip_rev.ptr.as_ref())
+                        .and_then(|ptrs| ptrs.first())
+                        .map(|ip| ip.to_string()),
+                    helo: (!self.data.helo_domain.is_empty())
+                        .then(|| self.data.helo_domain.clone()),
+                    active_connections: 1,
+                },
+                sasl: self.authenticated_as().map(|name| Sasl {
+                    login: name.into(),
+                    method: None,
+                }),
+                tls: (!tls_version.is_empty()).then(|| Tls {
+                    version: tls_version.as_ref().into(),
+                    cipher: tls_cipher.as_ref().into(),
+                    bits: None,
+                    issuer: None,
+                    subject: None,
+                }),
+                server: Server {
+                    name: Some(DAEMON_NAME.into()),
+                    port: self.data.local_port,
+                    ip: self.data.local_ip.to_string().into(),
+                },
+                queue: queue_id.map(|id| Queue {
+                    id: format!("{:x}", id),
+                }),
+                protocol: Protocol { version: 1 },
+            },
+            envelope: self.data.mail_from.as_ref().map(|from| Envelope {
+                from: Address {
+                    address: from.address_lcase.clone(),
+                    parameters: None,
+                },
+                to: self
+                    .data
+                    .rcpt_to
+                    .iter()
+                    .map(|to| Address {
+                        address: to.address_lcase.clone(),
+                        parameters: None,
+                    })
+                    .collect(),
+            }),
+            message: message.map(|message| Message {
+                headers: message
+                    .raw_parsed_headers()
+                    .iter()
+                    .map(|(k, v)| {
+                        (
+                            String::from_utf8_lossy(k).into_owned(),
+                            String::from_utf8_lossy(v).into_owned(),
+                        )
+                    })
+                    .collect(),
+                server_headers: vec![],
+                contents: String::from_utf8_lossy(message.raw_body()).into_owned(),
+                size: message.raw_message().len(),
+            }),
+        };
+
+        send_mta_hook_request(mta_hook, request).await
+    }
+}
+
+fn flatten_parameters(parameters: AHashMap<String, Option<String>>) -> String {
+    let mut arguments = String::new();
+    for (key, value) in parameters {
+        if !arguments.is_empty() {
+            arguments.push(' ');
+        }
+        arguments.push_str(key.as_str());
+        if let Some(value) = value {
+            arguments.push('=');
+            arguments.push_str(value.as_str());
+        }
+    }
+
+    arguments
+}

crates/smtp/src/inbound/hooks/mod.rs

@@ -0,0 +1,207 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+pub mod client;
+pub mod message;
+
+use ahash::AHashMap;
+
+use serde::{Deserialize, Serialize};
+
+#[derive(Serialize, Deserialize)]
+pub struct Request {
+    pub context: Context,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub envelope: Option<Envelope>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub message: Option<Message>,
+}
+
+#[derive(Serialize, Deserialize)]
+pub struct Context {
+    pub stage: Stage,
+    pub client: Client,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub sasl: Option<Sasl>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub tls: Option<Tls>,
+    pub server: Server,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub queue: Option<Queue>,
+    pub protocol: Protocol,
+}
+
+#[derive(Serialize, Deserialize)]
+pub struct Sasl {
+    pub login: String,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub method: Option<String>,
+}
+
+#[derive(Serialize, Deserialize)]
+pub struct Client {
+    pub ip: String,
+    pub port: u16,
+    pub ptr: Option<String>,
+    pub helo: Option<String>,
+    #[serde(rename = "activeConnections")]
+    pub active_connections: u32,
+}
+
+#[derive(Serialize, Deserialize)]
+pub struct Tls {
+    pub version: String,
+    pub cipher: String,
+    #[serde(rename = "cipherBits")]
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub bits: Option<u16>,
+    #[serde(rename = "certIssuer")]
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub issuer: Option<String>,
+    #[serde(rename = "certSubject")]
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub subject: Option<String>,
+}
+
+#[derive(Serialize, Deserialize)]
+pub struct Server {
+    pub name: Option<String>,
+    pub port: u16,
+    pub ip: Option<String>,
+}
+
+#[derive(Serialize, Deserialize)]
+pub struct Queue {
+    pub id: String,
+}
+
+#[derive(Serialize, Deserialize)]
+pub struct Protocol {
+    pub version: u32,
+}
+
+#[derive(Serialize, Deserialize)]
+pub enum Stage {
+    #[serde(rename = "connect")]
+    Connect,
+    #[serde(rename = "ehlo")]
+    Ehlo,
+    #[serde(rename = "auth")]
+    Auth,
+    #[serde(rename = "mail")]
+    Mail,
+    #[serde(rename = "rcpt")]
+    Rcpt,
+    #[serde(rename = "data")]
+    Data,
+}
+
+#[derive(Serialize, Deserialize)]
+pub struct Address {
+    pub address: String,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub parameters: Option<AHashMap<String, String>>,
+}
+
+#[derive(Serialize, Deserialize)]
+pub struct Envelope {
+    pub from: Address,
+    pub to: Vec<Address>,
+}
+
+#[derive(Serialize, Deserialize)]
+pub struct Message {
+    pub headers: Vec<(String, String)>,
+    #[serde(skip_serializing_if = "Vec::is_empty")]
+    #[serde(rename = "serverHeaders")]
+    #[serde(default)]
+    pub server_headers: Vec<(String, String)>,
+    pub contents: String,
+    pub size: usize,
+}
+
+#[derive(Serialize, Deserialize)]
+pub struct Response {
+    pub action: Action,
+    #[serde(default)]
+    pub response: Option<SmtpResponse>,
+    #[serde(default)]
+    pub modifications: Vec<Modification>,
+}
+
+#[derive(Serialize, Deserialize)]
+pub enum Action {
+    #[serde(rename = "accept")]
+    Accept,
+    #[serde(rename = "discard")]
+    Discard,
+    #[serde(rename = "reject")]
+    Reject,
+    #[serde(rename = "quarantine")]
+    Quarantine,
+}
+
+#[derive(Serialize, Deserialize, Default)]
+pub struct SmtpResponse {
+    #[serde(default)]
+    pub status: Option<u16>,
+    #[serde(default)]
+    pub enhanced_status: Option<String>,
+    #[serde(default)]
+    pub message: Option<String>,
+    #[serde(default)]
+    pub disconnect: bool,
+}
+
+#[derive(Serialize, Deserialize, Debug)]
+#[serde(tag = "type")]
+pub enum Modification {
+    #[serde(rename = "changeFrom")]
+    ChangeFrom {
+        value: String,
+        #[serde(default)]
+        parameters: AHashMap<String, Option<String>>,
+    },
+    #[serde(rename = "addRecipient")]
+    AddRecipient {
+        value: String,
+        #[serde(default)]
+        parameters: AHashMap<String, Option<String>>,
+    },
+    #[serde(rename = "deleteRecipient")]
+    DeleteRecipient { value: String },
+    #[serde(rename = "replaceContents")]
+    ReplaceContents { value: String },
+    #[serde(rename = "addHeader")]
+    AddHeader { name: String, value: String },
+    #[serde(rename = "insertHeader")]
+    InsertHeader {
+        index: u32,
+        name: String,
+        value: String,
+    },
+    #[serde(rename = "changeHeader")]
+    ChangeHeader {
+        index: u32,
+        name: String,
+        value: String,
+    },
+    #[serde(rename = "deleteHeader")]
+    DeleteHeader { index: u32, name: String },
+}
+
+impl From<common::config::smtp::session::Stage> for Stage {
+    fn from(value: common::config::smtp::session::Stage) -> Self {
+        match value {
+            common::config::smtp::session::Stage::Connect => Stage::Connect,
+            common::config::smtp::session::Stage::Ehlo => Stage::Ehlo,
+            common::config::smtp::session::Stage::Auth => Stage::Auth,
+            common::config::smtp::session::Stage::Mail => Stage::Mail,
+            common::config::smtp::session::Stage::Rcpt => Stage::Rcpt,
+            common::config::smtp::session::Stage::Data => Stage::Data,
+        }
+    }
+}

crates/smtp/src/inbound/mail.rs

@@ -0,0 +1,607 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use crate::{
+    core::{Session, SessionAddress},
+    scripts::ScriptResult,
+};
+use common::{config::smtp::session::Stage, network::SessionStream, scripts::ScriptModification};
+use mail_auth::{IprevOutput, IprevResult, SpfOutput, SpfResult, spf::verify::SpfParameters};
+use mail_parser::DateTime;
+use registry::schema::structs::Rate;
+use smtp_proto::{MAIL_BY_NOTIFY, MAIL_BY_RETURN, MAIL_REQUIRETLS, MailFrom, MtPriority};
+use std::{
+    borrow::Cow,
+    time::{Duration, Instant, SystemTime},
+};
+use trc::SmtpEvent;
+use utils::DomainPart;
+
+impl<T: SessionStream> Session<T> {
+    pub async fn handle_mail_from(&mut self, from: MailFrom<Cow<'_, str>>) -> Result<(), ()> {
+        if self.data.helo_domain.is_empty()
+            && (self.params.ehlo_require
+                || self.params.spf_ehlo.verify()
+                || self.params.spf_mail_from.verify())
+        {
+            trc::event!(
+                Smtp(SmtpEvent::DidNotSayEhlo),
+                SpanId = self.data.session_id,
+            );
+
+            return self
+                .write(b"503 5.5.1 Polite people say EHLO first.\r\n")
+                .await;
+        } else if self.data.mail_from.is_some() {
+            trc::event!(
+                Smtp(SmtpEvent::MultipleMailFrom),
+                SpanId = self.data.session_id,
+            );
+
+            return self
+                .write(b"503 5.5.1 Multiple MAIL commands not allowed.\r\n")
+                .await;
+        } else if self.params.auth_require && !self.is_authenticated() {
+            trc::event!(
+                Smtp(SmtpEvent::MailFromUnauthenticated),
+                SpanId = self.data.session_id,
+            );
+
+            return self
+                .write(b"503 5.5.1 You must authenticate first.\r\n")
+                .await;
+        } else if self.data.iprev.is_none() && self.params.iprev.verify() {
+            let time = Instant::now();
+            let iprev = self
+                .server
+                .core
+                .smtp
+                .resolvers
+                .dns
+                .verify_iprev(
+                    self.server
+                        .inner
+                        .cache
+                        .build_auth_parameters(self.data.remote_ip),
+                )
+                .await;
+
+            trc::event!(
+                Smtp(if matches!(iprev.result(), IprevResult::Pass) {
+                    SmtpEvent::IprevPass
+                } else {
+                    SmtpEvent::IprevFail
+                }),
+                SpanId = self.data.session_id,
+                Domain = self.data.helo_domain.clone(),
+                Result = trc::Error::from(&iprev),
+                Elapsed = time.elapsed(),
+            );
+
+            self.data.iprev = iprev.into();
+        }
+
+        // In strict mode reject messages from hosts that fail the reverse DNS lookup check
+        if self.params.iprev.is_strict()
+            && !matches!(
+                &self.data.iprev,
+                Some(IprevOutput {
+                    result: IprevResult::Pass,
+                    ..
+                })
+            )
+        {
+            let message = if matches!(
+                &self.data.iprev,
+                Some(IprevOutput {
+                    result: IprevResult::TempError(_),
+                    ..
+                })
+            ) {
+                &b"451 4.7.25 Temporary error validating reverse DNS.\r\n"[..]
+            } else {
+                &b"550 5.7.25 Reverse DNS validation failed.\r\n"[..]
+            };
+
+            return self.write(message).await;
+        }
+
+        let (address, address_lcase, domain) = if !from.address.is_empty() {
+            let address_lcase = from.address.to_lowercase_address(true);
+            let domain = address_lcase.domain_part().into();
+            (from.address.into_owned(), address_lcase, domain)
+        } else {
+            (String::new(), String::new(), String::new())
+        };
+
+        let has_dsn = from.env_id.is_some();
+        self.data.mail_from = SessionAddress {
+            address,
+            address_lcase,
+            domain,
+            flags: from.flags,
+            dsn_info: from.env_id.map(|e| e.into_owned()),
+        }
+        .into();
+
+        // Check whether the address is allowed
+        if !self
+            .server
+            .eval_if::<bool, _>(
+                &self.server.core.smtp.session.mail.is_allowed,
+                self,
+                self.data.session_id,
+            )
+            .await
+            .unwrap_or(true)
+        {
+            let mail_from = self.data.mail_from.take().unwrap();
+            trc::event!(
+                Smtp(SmtpEvent::MailFromNotAllowed),
+                From = mail_from.address_lcase,
+                SpanId = self.data.session_id,
+            );
+            return self
+                .write(b"550 5.7.1 Sender address not allowed.\r\n")
+                .await;
+        }
+
+        // Sieve filtering
+        if let Some((script, script_id)) = self
+            .server
+            .eval_if::<String, _>(
+                &self.server.core.smtp.session.mail.script,
+                self,
+                self.data.session_id,
+            )
+            .await
+            .and_then(|name| {
+                self.server
+                    .get_trusted_sieve_script(&name, self.data.session_id)
+                    .map(|s| (s, name))
+            })
+        {
+            match self
+                .run_script(
+                    script_id,
+                    script.clone(),
+                    self.build_script_parameters("mail"),
+                )
+                .await
+            {
+                ScriptResult::Accept { modifications } if !modifications.is_empty() => {
+                    for modification in modifications {
+                        if let ScriptModification::SetEnvelope { name, value } = modification {
+                            self.data.apply_envelope_modification(name, value);
+                        }
+                    }
+                }
+                ScriptResult::Reject(message) => {
+                    self.data.mail_from = None;
+                    return self.write(message.as_bytes()).await;
+                }
+                _ => (),
+            }
+        }
+
+        // Milter filtering
+        if let Err(message) = self.run_milters(Stage::Mail, None, None).await {
+            self.data.mail_from = None;
+            return self.write(message.message.as_bytes()).await;
+        }
+
+        // MTAHook filtering
+        if let Err(message) = self.run_mta_hooks(Stage::Mail, None, None).await {
+            self.data.mail_from = None;
+            return self.write(message.message.as_bytes()).await;
+        }
+
+        // Address rewriting
+        if let Some(new_address) = self
+            .server
+            .eval_if::<String, _>(
+                &self.server.core.smtp.session.mail.rewrite,
+                self,
+                self.data.session_id,
+            )
+            .await
+        {
+            let mail_from = self.data.mail_from.as_mut().unwrap();
+
+            trc::event!(
+                Smtp(SmtpEvent::MailFromRewritten),
+                SpanId = self.data.session_id,
+                Details = mail_from.address_lcase.clone(),
+                From = new_address.clone(),
+            );
+
+            if new_address.contains('@') {
+                mail_from.address_lcase = new_address.to_lowercase_address(true);
+                mail_from.domain = mail_from.address_lcase.domain_part().into();
+                mail_from.address = new_address;
+            } else if new_address.is_empty() {
+                mail_from.address_lcase.clear();
+                mail_from.domain.clear();
+                mail_from.address.clear();
+            }
+        }
+
+        // Make sure that the authenticated user is allowed to send from this address
+        match self.authenticated_as() {
+            Some(authenticated_as)
+                if self
+                    .server
+                    .eval_if(
+                        &self.server.core.smtp.session.auth.must_match_sender,
+                        self,
+                        self.data.session_id,
+                    )
+                    .await
+                    .unwrap_or(true) =>
+            {
+                let address_lcase = self.data.mail_from.as_ref().unwrap().address_lcase.as_str();
+                if authenticated_as != address_lcase
+                    && !self
+                        .authenticated_emails()
+                        .iter()
+                        .any(|e| e == address_lcase)
+                {
+                    trc::event!(
+                        Smtp(SmtpEvent::MailFromUnauthorized),
+                        SpanId = self.data.session_id,
+                        From = address_lcase.to_string(),
+                        Details = [trc::Value::String(authenticated_as.into())]
+                            .into_iter()
+                            .chain(
+                                self.authenticated_emails()
+                                    .iter()
+                                    .map(|e| trc::Value::String(e.into()))
+                            )
+                            .collect::<Vec<_>>()
+                    );
+                    self.data.mail_from = None;
+                    return self
+                        .write(b"501 5.5.4 You are not allowed to send from this address.\r\n")
+                        .await;
+                }
+            }
+            _ => (),
+        }
+
+        // Validate parameters
+        let config = &self.server.core.smtp.session.extensions;
+        let config_data = &self.server.core.smtp.session.data;
+        if (from.flags & MAIL_REQUIRETLS) != 0
+            && !self
+                .server
+                .eval_if(&config.requiretls, self, self.data.session_id)
+                .await
+                .unwrap_or(false)
+        {
+            trc::event!(
+                Smtp(SmtpEvent::RequireTlsDisabled),
+                SpanId = self.data.session_id,
+            );
+            self.data.mail_from = None;
+            return self
+                .write(b"501 5.5.4 REQUIRETLS has been disabled.\r\n")
+                .await;
+        }
+        if (from.flags & (MAIL_BY_NOTIFY | MAIL_BY_RETURN)) != 0 {
+            if let Some(duration) = self
+                .server
+                .eval_if::<Duration, _>(&config.deliver_by, self, self.data.session_id)
+                .await
+            {
+                if from.by.checked_abs().unwrap_or(0) as u64 <= duration.as_secs()
+                    && (from.by.is_positive() || (from.flags & MAIL_BY_NOTIFY) != 0)
+                {
+                    self.data.delivery_by = from.by;
+                } else {
+                    self.data.mail_from = None;
+
+                    trc::event!(
+                        Smtp(SmtpEvent::DeliverByInvalid),
+                        SpanId = self.data.session_id,
+                        Details = from.by,
+                    );
+
+                    return self
+                        .write(
+                            format!(
+                                "501 5.5.4 BY parameter exceeds maximum of {} seconds.\r\n",
+                                duration.as_secs()
+                            )
+                            .as_bytes(),
+                        )
+                        .await;
+                }
+            } else {
+                trc::event!(
+                    Smtp(SmtpEvent::DeliverByDisabled),
+                    SpanId = self.data.session_id,
+                );
+                self.data.mail_from = None;
+                return self
+                    .write(b"501 5.5.4 DELIVERBY extension has been disabled.\r\n")
+                    .await;
+            }
+        }
+        if from.mt_priority != 0 {
+            if self
+                .server
+                .eval_if::<MtPriority, _>(&config.mt_priority, self, self.data.session_id)
+                .await
+                .is_some()
+            {
+                if (-6..6).contains(&from.mt_priority) {
+                    self.data.priority = from.mt_priority as i16;
+                } else {
+                    trc::event!(
+                        Smtp(SmtpEvent::MtPriorityInvalid),
+                        SpanId = self.data.session_id,
+                        Details = from.mt_priority,
+                    );
+                    self.data.mail_from = None;
+                    return self.write(b"501 5.5.4 Invalid priority value.\r\n").await;
+                }
+            } else {
+                trc::event!(
+                    Smtp(SmtpEvent::MtPriorityDisabled),
+                    SpanId = self.data.session_id,
+                );
+                self.data.mail_from = None;
+                return self
+                    .write(b"501 5.5.4 MT-PRIORITY extension has been disabled.\r\n")
+                    .await;
+            }
+        }
+        if from.size > 0 {
+            let max_message_size = self
+                .server
+                .eval_if::<usize, _>(&config_data.max_message_size, self, self.data.session_id)
+                .await
+                .unwrap_or(25 * 1024 * 1024);
+
+            if max_message_size > 0 && from.size > max_message_size {
+                trc::event!(
+                    Smtp(SmtpEvent::MessageTooLarge),
+                    SpanId = self.data.session_id,
+                    Size = from.size,
+                    Limit = max_message_size,
+                );
+
+                self.data.mail_from = None;
+                return self
+                    .write(b"552 5.3.4 Message too big for system.\r\n")
+                    .await;
+            }
+        }
+
+        if from.hold_for != 0 || from.hold_until != 0 {
+            if from.hold_for != 0 && from.hold_until != 0 {
+                trc::event!(
+                    Smtp(SmtpEvent::FutureReleaseInvalid),
+                    SpanId = self.data.session_id,
+                    Details = "Both HOLDFOR and HOLDUNTIL were specified",
+                );
+                self.data.mail_from = None;
+                return self
+                    .write(b"501 5.5.4 Only one of HOLDFOR or HOLDUNTIL may be specified.\r\n")
+                    .await;
+            }
+            if let Some(max_hold) = self
+                .server
+                .eval_if::<Duration, _>(&config.future_release, self, self.data.session_id)
+                .await
+            {
+                let max_hold = max_hold.as_secs();
+                let now = SystemTime::now()
+                    .duration_since(SystemTime::UNIX_EPOCH)
+                    .map_or(0, |d| d.as_secs());
+                let hold_for = if from.hold_for != 0 {
+                    from.hold_for
+                } else if from.hold_until > now {
+                    from.hold_until - now
+                } else {
+                    trc::event!(
+                        Smtp(SmtpEvent::FutureReleaseInvalid),
+                        SpanId = self.data.session_id,
+                        Details = from.hold_until,
+                    );
+                    self.data.mail_from = None;
+                    return self
+                        .write(b"501 5.5.4 HOLDUNTIL must be a date and time in the future.\r\n")
+                        .await;
+                };
+                if hold_for <= max_hold {
+                    self.data.future_release = hold_for;
+                } else {
+                    trc::event!(
+                        Smtp(SmtpEvent::FutureReleaseInvalid),
+                        SpanId = self.data.session_id,
+                        Details = hold_for,
+                    );
+                    self.data.mail_from = None;
+                    let response = if from.hold_for != 0 {
+                        format!(
+                            "501 5.5.4 Requested hold time exceeds maximum of {max_hold} seconds.\r\n"
+                        )
+                    } else {
+                        format!(
+                            "501 5.5.4 Requested release time exceeds maximum of {}.\r\n",
+                            DateTime::from_timestamp((now + max_hold) as i64).to_rfc3339()
+                        )
+                    };
+                    return self.write(response.as_bytes()).await;
+                }
+            } else {
+                trc::event!(
+                    Smtp(SmtpEvent::FutureReleaseDisabled),
+                    SpanId = self.data.session_id,
+                );
+                self.data.mail_from = None;
+                return self
+                    .write(b"501 5.5.4 FUTURERELEASE extension has been disabled.\r\n")
+                    .await;
+            }
+        }
+        if has_dsn
+            && !self
+                .server
+                .eval_if(&config.dsn, self, self.data.session_id)
+                .await
+                .unwrap_or(false)
+        {
+            trc::event!(Smtp(SmtpEvent::DsnDisabled), SpanId = self.data.session_id,);
+            self.data.mail_from = None;
+            return self
+                .write(b"501 5.5.4 DSN extension has been disabled.\r\n")
+                .await;
+        }
+
+        if self.is_allowed().await {
+            // Verify SPF
+            if self.params.spf_mail_from.verify() {
+                let time = Instant::now();
+                let mail_from = self.data.mail_from.as_ref().unwrap();
+                let spf_output = if !mail_from.address.is_empty() {
+                    self.server
+                        .core
+                        .smtp
+                        .resolvers
+                        .dns
+                        .check_host(self.server.inner.cache.build_auth_parameters(
+                            SpfParameters::new(
+                                self.data.remote_ip,
+                                &mail_from.domain,
+                                &self.data.helo_domain,
+                                &self.hostname,
+                                &mail_from.address_lcase,
+                            ),
+                        ))
+                        .await
+                } else {
+                    self.server
+                        .core
+                        .smtp
+                        .resolvers
+                        .dns
+                        .check_host(self.server.inner.cache.build_auth_parameters(
+                            SpfParameters::new(
+                                self.data.remote_ip,
+                                &self.data.helo_domain,
+                                &self.data.helo_domain,
+                                &self.hostname,
+                                &format!("postmaster@{}", self.data.helo_domain),
+                            ),
+                        ))
+                        .await
+                };
+
+                trc::event!(
+                    Smtp(if matches!(spf_output.result(), SpfResult::Pass) {
+                        SmtpEvent::SpfFromPass
+                    } else {
+                        SmtpEvent::SpfFromFail
+                    }),
+                    SpanId = self.data.session_id,
+                    Domain = self.data.helo_domain.clone(),
+                    From = if !mail_from.address.is_empty() {
+                        mail_from.address.as_str()
+                    } else {
+                        "<>"
+                    }
+                    .to_string(),
+                    Result = trc::Error::from(&spf_output),
+                    Elapsed = time.elapsed(),
+                );
+
+                if self
+                    .handle_spf(&spf_output, self.params.spf_mail_from.is_strict())
+                    .await?
+                {
+                    self.data.spf_mail_from = spf_output.into();
+                } else {
+                    self.data.mail_from = None;
+                    return Ok(());
+                }
+            }
+
+            trc::event!(
+                Smtp(SmtpEvent::MailFrom),
+                SpanId = self.data.session_id,
+                From = self.data.mail_from.as_ref().unwrap().address_lcase.clone(),
+            );
+
+            self.eval_rcpt_params().await;
+            self.write(b"250 2.1.0 OK\r\n").await
+        } else {
+            trc::event!(
+                Smtp(SmtpEvent::RateLimitExceeded),
+                SpanId = self.data.session_id,
+                From = self.data.mail_from.as_ref().unwrap().address_lcase.clone(),
+            );
+
+            self.data.mail_from = None;
+            self.write(b"452 4.4.5 Rate limit exceeded, try again later.\r\n")
+                .await
+        }
+    }
+
+    pub async fn handle_spf(&mut self, spf_output: &SpfOutput, strict: bool) -> Result<bool, ()> {
+        let result = match spf_output.result() {
+            SpfResult::Pass => true,
+            SpfResult::TempError if strict => {
+                self.write(b"451 4.7.24 Temporary SPF validation error.\r\n")
+                    .await?;
+                false
+            }
+            result => {
+                if strict {
+                    self.write(
+                        format!("550 5.7.23 SPF validation failed, status: {result}.\r\n")
+                            .as_bytes(),
+                    )
+                    .await?;
+                    false
+                } else {
+                    true
+                }
+            }
+        };
+
+        // Send report
+        if let (Some(recipient), Some(rate)) = (
+            spf_output.report_address(),
+            self.server
+                .eval_if::<Rate, _>(
+                    &self.server.core.smtp.report.spf.send,
+                    self,
+                    self.data.session_id,
+                )
+                .await,
+        ) {
+            // Do not send SPF auth failures to local domains, as they are likely relay attempts (which are blocked later on)
+            match self.server.domain(recipient.domain_part()).await {
+                Ok(Some(_)) => return Ok(result),
+                Ok(None) => (),
+                Err(err) => {
+                    trc::error!(
+                        err.caused_by(trc::location!())
+                            .span_id(self.data.session_id)
+                            .details("Failed to lookup local domain")
+                    );
+                }
+            }
+
+            self.send_spf_report(recipient, &rate, !result, spf_output)
+                .await;
+        }
+
+        Ok(result)
+    }
+}

crates/smtp/src/inbound/milter/client.rs

@@ -0,0 +1,368 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use common::config::smtp::session::Milter;
+use rustls_pki_types::ServerName;
+use tokio::{
+    io::{AsyncRead, AsyncReadExt, AsyncWrite, AsyncWriteExt},
+    net::TcpStream,
+};
+use tokio_rustls::{TlsConnector, client::TlsStream};
+use trc::MilterEvent;
+
+use super::{
+    protocol::{SMFIC_CONNECT, SMFIC_HELO, SMFIC_MAIL, SMFIC_RCPT},
+    receiver::{FrameResult, Receiver},
+    *,
+};
+
+const MILTER_CHUNK_SIZE: usize = 65535;
+
+impl MilterClient<TcpStream> {
+    pub async fn connect(config: &Milter, session_id: u64) -> Result<Self> {
+        tokio::time::timeout(config.timeout_command, async {
+            let mut last_err = Error::Disconnected;
+            for addr in &config.addrs {
+                match TcpStream::connect(addr).await {
+                    Ok(stream) => {
+                        return Ok(MilterClient {
+                            stream,
+                            timeout_cmd: config.timeout_command,
+                            timeout_data: config.timeout_data,
+                            buf: vec![0u8; 8192],
+                            bytes_read: 0,
+                            receiver: Receiver::with_max_frame_len(config.max_frame_len),
+                            options: 0,
+                            version: config.protocol_version,
+                            session_id,
+                            flags_actions: config.flags_actions.unwrap_or(
+                                SMFIF_ADDHDRS
+                                    | SMFIF_CHGBODY
+                                    | SMFIF_ADDRCPT
+                                    | SMFIF_DELRCPT
+                                    | SMFIF_CHGHDRS
+                                    | SMFIF_QUARANTINE
+                                    | SMFIF_CHGFROM
+                                    | SMFIF_ADDRCPT_PAR,
+                            ),
+                            flags_protocol: config.flags_protocol.unwrap_or(0x42),
+                            id: config.id,
+                        });
+                    }
+                    Err(err) => {
+                        last_err = Error::Io(err);
+                    }
+                }
+            }
+            Err(last_err)
+        })
+        .await
+        .map_err(|_| Error::Timeout)?
+    }
+
+    pub async fn into_tls(
+        self,
+        tls_connector: &TlsConnector,
+        tls_hostname: &str,
+    ) -> Result<MilterClient<TlsStream<TcpStream>>> {
+        tokio::time::timeout(self.timeout_cmd, async {
+            Ok(MilterClient {
+                stream: tls_connector
+                    .connect(
+                        ServerName::try_from(tls_hostname)
+                            .map_err(|_| Error::TLSInvalidName)?
+                            .to_owned(),
+                        self.stream,
+                    )
+                    .await?,
+                buf: self.buf,
+                timeout_cmd: self.timeout_cmd,
+                timeout_data: self.timeout_data,
+                receiver: self.receiver,
+                bytes_read: self.bytes_read,
+                options: self.options,
+                version: self.version,
+                session_id: self.session_id,
+                flags_actions: self.flags_actions,
+                flags_protocol: self.flags_protocol,
+                id: self.id,
+            })
+        })
+        .await
+        .map_err(|_| Error::Timeout)?
+    }
+}
+
+impl<T: AsyncRead + AsyncWrite + Unpin> MilterClient<T> {
+    pub async fn init(&mut self) -> super::Result<Options> {
+        self.write(Command::OptionNegotiation(Options {
+            version: match self.version {
+                MilterVersion::V2 => 2,
+                MilterVersion::V6 => 6,
+            },
+            actions: self.flags_actions,
+            protocol: self.flags_protocol,
+        }))
+        .await?;
+        match self.read().await? {
+            Response::OptionNegotiation(options) => {
+                self.options = options.protocol;
+                Ok(options)
+            }
+            response => Err(Error::Unexpected(response)),
+        }
+    }
+
+    pub async fn connection(
+        &mut self,
+        hostname: impl AsRef<[u8]>,
+        remote_ip: IpAddr,
+        remote_port: u16,
+        macros: Macros<'_>,
+    ) -> super::Result<Action> {
+        if !self.has_option(SMFIP_NOCONNECT) {
+            self.write(Command::Macro {
+                macros: macros.with_cmd_code(SMFIC_CONNECT),
+            })
+            .await?;
+            self.write(Command::Connect {
+                hostname: hostname.as_ref(),
+                port: remote_port,
+                address: remote_ip,
+            })
+            .await?;
+            if !self.has_option(SMFIP_NR_CONN) {
+                return self.read().await?.into_action();
+            }
+        }
+
+        Ok(Action::Accept)
+    }
+
+    pub async fn helo(
+        &mut self,
+        hostname: impl AsRef<[u8]>,
+        macros: Macros<'_>,
+    ) -> super::Result<Action> {
+        if !self.has_option(SMFIP_NOHELO) {
+            self.write(Command::Macro {
+                macros: macros.with_cmd_code(SMFIC_HELO),
+            })
+            .await?;
+            self.write(Command::Helo {
+                hostname: hostname.as_ref(),
+            })
+            .await?;
+            if !self.has_option(SMFIP_NR_HELO) {
+                return self.read().await?.into_action();
+            }
+        }
+        Ok(Action::Accept)
+    }
+
+    pub async fn mail_from<A, V>(
+        &mut self,
+        addr: A,
+        params: Option<&[V]>,
+        macros: Macros<'_>,
+    ) -> super::Result<Action>
+    where
+        A: AsRef<[u8]>,
+        V: AsRef<[u8]>,
+    {
+        if !self.has_option(SMFIP_NOMAIL) {
+            self.write(Command::Macro {
+                macros: macros.with_cmd_code(SMFIC_MAIL),
+            })
+            .await?;
+            self.write(Command::MailFrom {
+                sender: addr.as_ref(),
+                args: params.map(|params| params.iter().map(|value| value.as_ref()).collect()),
+            })
+            .await?;
+            if !self.has_option(SMFIP_NR_MAIL) {
+                return self.read().await?.into_action();
+            }
+        }
+        Ok(Action::Accept)
+    }
+
+    pub async fn rcpt_to<A, V>(
+        &mut self,
+        addr: A,
+        params: Option<&[V]>,
+        macros: Macros<'_>,
+    ) -> super::Result<Action>
+    where
+        A: AsRef<[u8]>,
+        V: AsRef<[u8]>,
+    {
+        if !self.has_option(SMFIP_NORCPT) {
+            self.write(Command::Macro {
+                macros: macros.with_cmd_code(SMFIC_RCPT),
+            })
+            .await?;
+            self.write(Command::Rcpt {
+                recipient: addr.as_ref(),
+                args: params.map(|params| params.iter().map(|value| value.as_ref()).collect()),
+            })
+            .await?;
+            if !self.has_option(SMFIP_NR_RCPT) {
+                return self.read().await?.into_action();
+            }
+        }
+        Ok(Action::Accept)
+    }
+
+    pub async fn headers<I, H, V>(&mut self, headers: I) -> super::Result<Action>
+    where
+        I: Iterator<Item = (H, V)>,
+        H: AsRef<str>,
+        V: AsRef<str>,
+    {
+        if !self.has_option(SMFIP_NOHDRS) {
+            for (name, value) in headers {
+                self.write(Command::Header {
+                    name: name.as_ref().trim().as_bytes(),
+                    value: value.as_ref().trim().as_bytes(),
+                })
+                .await?;
+                if !self.has_option(SMFIP_NR_HDR) {
+                    match self.read().await? {
+                        Response::Action(Action::Accept | Action::Continue) => (),
+                        Response::Action(action) => return Ok(action),
+                        response => return Err(Error::Unexpected(response)),
+                    }
+                }
+            }
+
+            // Write EndOfHeaders
+            self.write(Command::EndOfHeader).await?;
+            if !self.has_option(SMFIP_NR_EOH) {
+                return self.read().await?.into_action();
+            }
+        }
+        Ok(Action::Accept)
+    }
+
+    pub async fn data(&mut self) -> super::Result<Action> {
+        if matches!(self.version, MilterVersion::V6) && !self.has_option(SMFIP_NODATA) {
+            self.write(Command::Data).await?;
+            if !self.has_option(SMFIP_NR_DATA) {
+                return self.read().await?.into_action();
+            }
+        }
+        Ok(Action::Accept)
+    }
+
+    pub async fn body(&mut self, body: &[u8]) -> super::Result<(Action, Vec<Modification>)> {
+        if !self.has_option(SMFIP_NOBODY) {
+            // Write body chunks
+            for value in body.chunks(MILTER_CHUNK_SIZE) {
+                self.write(Command::Body { value }).await?;
+                if !self.has_option(SMFIP_NR_BODY) {
+                    match self.read().await? {
+                        Response::Action(Action::Accept | Action::Continue)
+                        | Response::Progress => (),
+                        Response::Skip => break,
+                        Response::Action(reject) => {
+                            return Ok((reject, Vec::new()));
+                        }
+                        response => return Err(Error::Unexpected(response)),
+                    }
+                }
+            }
+
+            // Write EndOfBody
+            self.write(Command::EndOfBody).await?;
+
+            // Collect responses
+            let mut modifications = Vec::new();
+            loop {
+                match self.read().await? {
+                    Response::Action(action) => {
+                        return Ok((action, modifications));
+                    }
+                    Response::Modification(modification) => {
+                        modifications.push(modification);
+                    }
+                    Response::Progress => (),
+                    unexpected => {
+                        return Err(Error::Unexpected(unexpected));
+                    }
+                }
+            }
+        } else {
+            Ok((Action::Accept, vec![]))
+        }
+    }
+
+    pub async fn abort(&mut self) -> super::Result<()> {
+        self.write(Command::Abort).await
+    }
+
+    pub async fn quit(&mut self) -> super::Result<()> {
+        self.write(Command::Quit).await
+    }
+
+    async fn write(&mut self, action: Command<'_>) -> super::Result<()> {
+        trc::event!(
+            Milter(MilterEvent::Write),
+            SpanId = self.session_id,
+            Id = self.id.to_string(),
+            Contents = action.to_string(),
+        );
+
+        tokio::time::timeout(self.timeout_cmd, async {
+            self.stream.write_all(action.serialize().as_ref()).await?;
+            self.stream.flush().await.map_err(Error::Io)
+        })
+        .await
+        .map_err(|_| Error::Timeout)?
+    }
+
+    async fn read(&mut self) -> super::Result<Response> {
+        loop {
+            match self.receiver.read_frame(&self.buf[..self.bytes_read]) {
+                FrameResult::Frame(frame) => {
+                    if let Some(response) = Response::deserialize(&frame) {
+                        trc::event!(
+                            Milter(MilterEvent::Read),
+                            SpanId = self.session_id,
+                            Id = self.id.to_string(),
+                            Contents = response.to_string(),
+                        );
+
+                        return Ok(response);
+                    } else {
+                        return Err(Error::FrameInvalid(frame.into_owned()));
+                    }
+                }
+                FrameResult::Incomplete => {
+                    self.bytes_read = tokio::time::timeout(self.timeout_data, async {
+                        self.stream.read(&mut self.buf).await.map_err(Error::Io)
+                    })
+                    .await
+                    .map_err(|_| Error::Timeout)??;
+                    if self.bytes_read == 0 {
+                        return Err(Error::Disconnected);
+                    }
+                }
+                FrameResult::TooLarge(size) => return Err(Error::FrameTooLarge(size)),
+            }
+        }
+    }
+
+    #[inline(always)]
+    fn has_option(&self, opt: u32) -> bool {
+        self.options & opt == opt
+    }
+
+    pub fn with_version(mut self, version: MilterVersion) -> Self {
+        self.version = version;
+        self
+    }
+}

crates/smtp/src/inbound/milter/macros.rs

@@ -0,0 +1,184 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use std::{borrow::Cow, net::IpAddr};
+
+use super::{Macro, Macros};
+
+pub trait IntoMacroValue<'x> {
+    fn into_macro_value(self) -> Cow<'x, [u8]>;
+}
+
+impl<'x> Macros<'x> {
+    pub fn new() -> Self {
+        Macros::default()
+    }
+
+    pub fn with_cmd_code(mut self, cmd_code: u8) -> Self {
+        self.cmdcode = cmd_code;
+        self
+    }
+
+    pub fn with_macro(mut self, name: &'static [u8], value: impl IntoMacroValue<'x>) -> Self {
+        self.macros.push(Macro {
+            name,
+            value: value.into_macro_value(),
+        });
+        self
+    }
+
+    pub fn with_queue_id(self, queue_id: impl IntoMacroValue<'x>) -> Self {
+        self.with_macro(b"i", queue_id)
+    }
+
+    pub fn with_local_hostname(self, my_hostname: impl IntoMacroValue<'x>) -> Self {
+        self.with_macro(b"j", my_hostname)
+    }
+
+    pub fn with_validated_client_name(self, client_name: impl IntoMacroValue<'x>) -> Self {
+        self.with_macro(b"_", client_name)
+    }
+
+    pub fn with_sasl_login_name(self, sasl_login_name: impl IntoMacroValue<'x>) -> Self {
+        self.with_macro(b"{auth_authen}", sasl_login_name)
+    }
+
+    pub fn with_sasl_sender(self, sasl_sender: impl IntoMacroValue<'x>) -> Self {
+        self.with_macro(b"{auth_author}", sasl_sender)
+    }
+
+    pub fn with_sasl_method(self, sasl_method: impl IntoMacroValue<'x>) -> Self {
+        self.with_macro(b"{auth_type}", sasl_method)
+    }
+
+    pub fn with_client_address(self, client_address: impl IntoMacroValue<'x>) -> Self {
+        self.with_macro(b"{client_addr}", client_address)
+    }
+
+    pub fn with_client_connections(self, client_connections: impl IntoMacroValue<'x>) -> Self {
+        self.with_macro(b"{client_connections}", client_connections)
+    }
+
+    pub fn with_client_name(self, client_name: impl IntoMacroValue<'x>) -> Self {
+        self.with_macro(b"{client_name}", client_name)
+    }
+
+    pub fn with_client_port(self, client_port: impl IntoMacroValue<'x>) -> Self {
+        self.with_macro(b"{client_port}", client_port)
+    }
+
+    pub fn with_client_ptr(self, client_ptr: impl IntoMacroValue<'x>) -> Self {
+        self.with_macro(b"{client_ptr}", client_ptr)
+    }
+
+    pub fn with_cert_issuer(self, cert_issuer: impl IntoMacroValue<'x>) -> Self {
+        self.with_macro(b"{cert_issuer}", cert_issuer)
+    }
+
+    pub fn with_cert_subject(self, cert_subject: impl IntoMacroValue<'x>) -> Self {
+        self.with_macro(b"{cert_subject}", cert_subject)
+    }
+
+    pub fn with_cipher_bits(self, cipher_bits: impl IntoMacroValue<'x>) -> Self {
+        self.with_macro(b"{cipher_bits}", cipher_bits)
+    }
+
+    pub fn with_cipher(self, cipher: impl IntoMacroValue<'x>) -> Self {
+        self.with_macro(b"{cipher}", cipher)
+    }
+
+    pub fn with_daemon_address(self, daemon_address: impl IntoMacroValue<'x>) -> Self {
+        self.with_macro(b"{daemon_addr}", daemon_address)
+    }
+
+    pub fn with_daemon_name(self, daemon_name: impl IntoMacroValue<'x>) -> Self {
+        self.with_macro(b"{daemon_name}", daemon_name)
+    }
+
+    pub fn with_daemon_port(self, daemon_port: impl IntoMacroValue<'x>) -> Self {
+        self.with_macro(b"{daemon_port}", daemon_port)
+    }
+
+    pub fn with_mail_address(self, mail_address: impl IntoMacroValue<'x>) -> Self {
+        self.with_macro(b"{mail_addr}", mail_address)
+    }
+
+    pub fn with_mail_host(self, mail_host_address: impl IntoMacroValue<'x>) -> Self {
+        self.with_macro(b"{mail_host}", mail_host_address)
+    }
+
+    pub fn with_mail_mailer(self, mail_mailer: impl IntoMacroValue<'x>) -> Self {
+        self.with_macro(b"{mail_mailer}", mail_mailer)
+    }
+
+    pub fn with_rcpt_address(self, rcpt_address: impl IntoMacroValue<'x>) -> Self {
+        self.with_macro(b"{rcpt_addr}", rcpt_address)
+    }
+
+    pub fn with_rcpt_host(self, rcpt_host: impl IntoMacroValue<'x>) -> Self {
+        self.with_macro(b"{rcpt_host}", rcpt_host)
+    }
+
+    pub fn with_rcpt_mailer(self, rcpt_mailer: impl IntoMacroValue<'x>) -> Self {
+        self.with_macro(b"{rcpt_mailer}", rcpt_mailer)
+    }
+
+    pub fn with_tls_version(self, tls_version: impl IntoMacroValue<'x>) -> Self {
+        self.with_macro(b"{tls_version}", tls_version)
+    }
+
+    pub fn with_version(self, version: impl IntoMacroValue<'x>) -> Self {
+        self.with_macro(b"{v}", version)
+    }
+}
+
+impl<'x> IntoMacroValue<'x> for IpAddr {
+    fn into_macro_value(self) -> Cow<'x, [u8]> {
+        Cow::Owned(self.to_string().into_bytes())
+    }
+}
+
+impl<'x> IntoMacroValue<'x> for u16 {
+    fn into_macro_value(self) -> Cow<'x, [u8]> {
+        Cow::Owned(self.to_string().into_bytes())
+    }
+}
+
+impl<'x> IntoMacroValue<'x> for &'x [u8] {
+    fn into_macro_value(self) -> Cow<'x, [u8]> {
+        Cow::Borrowed(self)
+    }
+}
+
+impl<'x> IntoMacroValue<'x> for &'x str {
+    fn into_macro_value(self) -> Cow<'x, [u8]> {
+        Cow::Borrowed(self.as_bytes())
+    }
+}
+
+impl<'x> IntoMacroValue<'x> for &'x String {
+    fn into_macro_value(self) -> Cow<'x, [u8]> {
+        Cow::Borrowed(self.as_bytes())
+    }
+}
+
+impl<'x> IntoMacroValue<'x> for String {
+    fn into_macro_value(self) -> Cow<'x, [u8]> {
+        Cow::Owned(self.into_bytes())
+    }
+}
+
+impl<'x> IntoMacroValue<'x> for Vec<u8> {
+    fn into_macro_value(self) -> Cow<'x, [u8]> {
+        Cow::Owned(self)
+    }
+}
+
+impl<'x> IntoMacroValue<'x> for &'x Vec<u8> {
+    fn into_macro_value(self) -> Cow<'x, [u8]> {
+        Cow::Borrowed(self)
+    }
+}

crates/smtp/src/inbound/milter/message.rs

@@ -0,0 +1,550 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use super::{Action, Error, Macros, Modification};
+use crate::{
+    core::{Session, SessionAddress, SessionData},
+    inbound::{FilterResponse, milter::MilterClient},
+    queue::QueueId,
+};
+use common::{
+    DAEMON_NAME,
+    config::smtp::session::{Milter, Stage},
+    network::SessionStream,
+};
+use mail_auth::AuthenticatedMessage;
+use smtp_proto::{IntoString, request::parser::Rfc5321Parser};
+use std::{borrow::Cow, time::Instant};
+use tokio::io::{AsyncRead, AsyncWrite};
+use trc::MilterEvent;
+use utils::DomainPart;
+
+enum Rejection {
+    Action(Action),
+    Error(Error),
+}
+
+impl<T: SessionStream> Session<T> {
+    pub async fn run_milters(
+        &self,
+        stage: Stage,
+        message: Option<&AuthenticatedMessage<'_>>,
+        queue_id: Option<QueueId>,
+    ) -> Result<Vec<Modification>, FilterResponse> {
+        let milters = &self.server.core.smtp.session.milters;
+        if milters.is_empty() {
+            return Ok(Vec::new());
+        }
+
+        let mut modifications = Vec::new();
+        for milter in milters {
+            if !milter.run_on_stage.contains(&stage)
+                || !self
+                    .server
+                    .eval_if(&milter.enable, self, self.data.session_id)
+                    .await
+                    .unwrap_or(false)
+            {
+                continue;
+            }
+
+            let time = Instant::now();
+            match self.connect_and_run(milter, message).await {
+                Ok(new_modifications) => {
+                    trc::event!(
+                        Milter(MilterEvent::ActionAccept),
+                        SpanId = self.data.session_id,
+                        Id = milter.id.to_string(),
+                        Elapsed = time.elapsed(),
+                    );
+
+                    if !modifications.is_empty() {
+                        // The message body can only be replaced once, so we need to remove
+                        // any previous replacements.
+                        if new_modifications
+                            .iter()
+                            .any(|m| matches!(m, Modification::ReplaceBody { .. }))
+                        {
+                            modifications
+                                .retain(|m| !matches!(m, Modification::ReplaceBody { .. }));
+                        }
+                        modifications.extend(new_modifications);
+                    } else {
+                        modifications = new_modifications;
+                    }
+                }
+                Err(Rejection::Action(action)) => {
+                    trc::event!(
+                        Milter(match &action {
+                            Action::Discard => MilterEvent::ActionDiscard,
+                            Action::Reject => MilterEvent::ActionReject,
+                            Action::TempFail => MilterEvent::ActionTempFail,
+                            Action::ReplyCode { .. } => {
+                                MilterEvent::ActionReplyCode
+                            }
+                            Action::Shutdown => MilterEvent::ActionShutdown,
+                            Action::ConnectionFailure => MilterEvent::ActionConnectionFailure,
+                            Action::Accept | Action::Continue => unreachable!(),
+                        }),
+                        SpanId = self.data.session_id,
+                        QueueId = queue_id,
+                        Id = milter.id.to_string(),
+                        Elapsed = time.elapsed(),
+                    );
+
+                    return Err(match action {
+                        Action::Discard => FilterResponse::accept(),
+                        Action::Reject => FilterResponse::reject(),
+                        Action::TempFail => FilterResponse::temp_fail(),
+                        Action::ReplyCode { code, text } => {
+                            let mut response = Vec::with_capacity(text.len() + 6);
+                            response.extend_from_slice(code.as_slice());
+                            response.push(b' ');
+                            response.extend_from_slice(text.as_bytes());
+                            if !text.ends_with('\n') {
+                                response.extend_from_slice(b"\r\n");
+                            }
+                            FilterResponse {
+                                message: response.into_string().into(),
+                                disconnect: false,
+                            }
+                        }
+                        Action::Shutdown => FilterResponse::shutdown(),
+                        Action::ConnectionFailure => FilterResponse::default().disconnect(),
+                        Action::Accept | Action::Continue => unreachable!(),
+                    });
+                }
+                Err(Rejection::Error(err)) => {
+                    let (code, details) = match err {
+                        Error::Io(details) => {
+                            (MilterEvent::IoError, trc::Value::from(details.to_string()))
+                        }
+                        Error::FrameTooLarge(size) => {
+                            (MilterEvent::FrameTooLarge, trc::Value::from(size))
+                        }
+                        Error::FrameInvalid(bytes) => {
+                            (MilterEvent::FrameInvalid, trc::Value::from(bytes))
+                        }
+                        Error::Unexpected(response) => (
+                            MilterEvent::UnexpectedResponse,
+                            trc::Value::from(response.to_string()),
+                        ),
+                        Error::Timeout => (MilterEvent::Timeout, trc::Value::None),
+                        Error::TLSInvalidName => (MilterEvent::TlsInvalidName, trc::Value::None),
+                        Error::Disconnected => (MilterEvent::Disconnected, trc::Value::None),
+                    };
+
+                    trc::event!(
+                        Milter(code),
+                        SpanId = self.data.session_id,
+                        Id = milter.id.to_string(),
+                        Details = details,
+                        Elapsed = time.elapsed(),
+                    );
+
+                    if milter.tempfail_on_error {
+                        return Err(FilterResponse::server_failure());
+                    }
+                }
+            }
+        }
+
+        Ok(modifications)
+    }
+
+    async fn connect_and_run(
+        &self,
+        milter: &Milter,
+        message: Option<&AuthenticatedMessage<'_>>,
+    ) -> Result<Vec<Modification>, Rejection> {
+        // Build client
+        let client = MilterClient::connect(milter, self.data.session_id).await?;
+        if !milter.tls {
+            self.run(client, message).await
+        } else {
+            self.run(
+                client
+                    .into_tls(
+                        if !milter.tls_allow_invalid_certs {
+                            &self.server.inner.data.smtp_connectors.pki_verify
+                        } else {
+                            &self.server.inner.data.smtp_connectors.dummy_verify
+                        },
+                        &milter.hostname,
+                    )
+                    .await?,
+                message,
+            )
+            .await
+        }
+    }
+
+    async fn run<S: AsyncRead + AsyncWrite + Unpin>(
+        &self,
+        mut client: MilterClient<S>,
+        message: Option<&AuthenticatedMessage<'_>>,
+    ) -> Result<Vec<Modification>, Rejection> {
+        // Option negotiation
+        client.init().await?;
+
+        // Connect stage
+        let client_ptr = self
+            .data
+            .iprev
+            .as_ref()
+            .and_then(|ip_rev| ip_rev.ptr.as_ref())
+            .and_then(|ptrs| ptrs.first())
+            .map(|s| s.as_ref());
+        client
+            .connection(
+                client_ptr.unwrap_or(self.data.helo_domain.as_str()),
+                self.data.remote_ip,
+                self.data.remote_port,
+                Macros::new()
+                    .with_daemon_name(DAEMON_NAME)
+                    .with_local_hostname(&self.hostname)
+                    .with_client_address(self.data.remote_ip)
+                    .with_client_port(self.data.remote_port)
+                    .with_client_ptr(client_ptr.unwrap_or("unknown")),
+            )
+            .await?
+            .assert_continue()?;
+
+        // EHLO/HELO
+        let (tls_version, tls_cipher) = self.stream.tls_version_and_cipher();
+        client
+            .helo(
+                &self.data.helo_domain,
+                Macros::new()
+                    .with_cipher(tls_cipher.as_ref())
+                    .with_tls_version(tls_version.as_ref()),
+            )
+            .await?
+            .assert_continue()?;
+
+        // Mail from
+        if let Some(mail_from) = &self.data.mail_from {
+            let addr = &mail_from.address_lcase;
+            client
+                .mail_from(
+                    &format!("<{addr}>"),
+                    None::<&[&str]>,
+                    if let Some(name) = self.authenticated_as() {
+                        Macros::new()
+                            .with_mail_address(addr)
+                            .with_sasl_login_name(name)
+                    } else {
+                        Macros::new().with_mail_address(addr)
+                    },
+                )
+                .await?
+                .assert_continue()?;
+
+            // Rcpt to
+            for rcpt in &self.data.rcpt_to {
+                client
+                    .rcpt_to(
+                        &format!("<{}>", rcpt.address_lcase),
+                        None::<&[&str]>,
+                        Macros::new().with_rcpt_address(&rcpt.address_lcase),
+                    )
+                    .await?
+                    .assert_continue()?;
+            }
+        }
+
+        if let Some(message) = message {
+            // Data
+            client.data().await?.assert_continue()?;
+
+            // Headers
+            client
+                .headers(message.raw_parsed_headers().iter().map(|(k, v)| {
+                    (
+                        std::str::from_utf8(k).unwrap_or_default(),
+                        std::str::from_utf8(v).unwrap_or_default(),
+                    )
+                }))
+                .await?
+                .assert_continue()?;
+
+            // Message body
+            let (action, modifications) = client.body(message.raw_message()).await?;
+            action.assert_continue()?;
+
+            // Quit
+            let _ = client.quit().await;
+
+            // Return modifications
+            Ok(modifications)
+        } else {
+            // Quit
+            let _ = client.quit().await;
+
+            Ok(Vec::new())
+        }
+    }
+}
+
+impl SessionData {
+    pub fn apply_milter_modifications(
+        &mut self,
+        modifications: Vec<Modification>,
+        message: &AuthenticatedMessage<'_>,
+    ) -> Option<Vec<u8>> {
+        let mut body = Vec::new();
+        let mut header_changes = Vec::new();
+        let mut needs_rewrite = false;
+
+        for modification in modifications {
+            match modification {
+                Modification::ChangeFrom { sender, mut args } => {
+                    // Change sender
+                    let sender = strip_brackets(&sender);
+                    let address_lcase = sender.to_lowercase();
+                    let mut mail_from = SessionAddress {
+                        domain: address_lcase.domain_part().into(),
+                        address_lcase,
+                        address: sender,
+                        flags: 0,
+                        dsn_info: None,
+                    };
+                    if !args.is_empty() {
+                        args.push('\n');
+                        match Rfc5321Parser::new(&mut args.as_bytes().iter())
+                            .mail_from_parameters(Cow::Borrowed(""))
+                        {
+                            Ok(addr) => {
+                                mail_from.flags = addr.flags;
+                                mail_from.dsn_info = addr.env_id.map(|e| e.into_owned());
+                            }
+                            Err(err) => {
+                                trc::event!(
+                                    Milter(MilterEvent::ParseError),
+                                    SpanId = self.session_id,
+                                    Details = "Failed to parse milter mailFrom parameters",
+                                    Reason = err.to_string(),
+                                );
+                            }
+                        }
+                    }
+                    self.mail_from = Some(mail_from);
+                }
+                Modification::AddRcpt {
+                    recipient,
+                    mut args,
+                } => {
+                    // Add recipient
+                    let recipient = strip_brackets(&recipient);
+                    if recipient.contains('@') {
+                        let address_lcase = recipient.to_lowercase();
+                        let mut rcpt = SessionAddress {
+                            domain: address_lcase.domain_part().into(),
+                            address_lcase,
+                            address: recipient,
+                            flags: 0,
+                            dsn_info: None,
+                        };
+                        if !args.is_empty() {
+                            args.push('\n');
+                            match Rfc5321Parser::new(&mut args.as_bytes().iter())
+                                .rcpt_to_parameters(Cow::Borrowed(""))
+                            {
+                                Ok(addr) => {
+                                    rcpt.flags = addr.flags;
+                                    rcpt.dsn_info = addr.orcpt.map(|e| e.into_owned());
+                                }
+                                Err(err) => {
+                                    trc::event!(
+                                        Milter(MilterEvent::ParseError),
+                                        SpanId = self.session_id,
+                                        Details = "Failed to parse milter rcptTo parameters",
+                                        Reason = err.to_string(),
+                                    );
+                                }
+                            }
+                        }
+
+                        if !self.rcpt_to.contains(&rcpt) {
+                            self.rcpt_to.push(rcpt);
+                        }
+                    }
+                }
+                Modification::DeleteRcpt { recipient } => {
+                    let recipient = strip_brackets(&recipient);
+                    self.rcpt_to.retain(|r| r.address_lcase != recipient);
+                }
+                Modification::ReplaceBody { value } => {
+                    body.extend(value);
+                }
+                Modification::AddHeader { name, value } => {
+                    header_changes.push((0, name, value, false));
+                }
+                Modification::InsertHeader { index, name, value } => {
+                    header_changes.push((index, name, value, false));
+                    needs_rewrite = true;
+                }
+                Modification::ChangeHeader { index, name, value } => {
+                    if value.is_empty()
+                        || message
+                            .raw_parsed_headers()
+                            .iter()
+                            .any(|(n, _)| n.eq_ignore_ascii_case(name.as_bytes()))
+                    {
+                        header_changes.push((index, name, value, true));
+                        needs_rewrite = true;
+                    } else {
+                        header_changes.push((0, name, value, false));
+                    }
+                }
+                Modification::Quarantine { reason } => {
+                    header_changes.push((0, "X-Quarantine".into(), reason, false));
+                }
+            }
+        }
+
+        // If there are no header changes return
+        if header_changes.is_empty() {
+            return if !body.is_empty() {
+                let mut new_message = Vec::with_capacity(body.len() + message.raw_headers().len());
+                new_message.extend_from_slice(message.raw_headers());
+                new_message.extend(body);
+                Some(new_message)
+            } else {
+                None
+            };
+        }
+
+        let new_body = if !body.is_empty() {
+            &body[..]
+        } else {
+            message.raw_body()
+        };
+
+        if needs_rewrite {
+            let mut headers = message
+                .raw_parsed_headers()
+                .iter()
+                .map(|(h, v)| (Cow::from(*h), Cow::from(*v)))
+                .collect::<Vec<_>>();
+
+            // Perform changes
+            for (index, header_name, header_value, is_change) in header_changes {
+                if is_change {
+                    let mut header_count = 0;
+                    for (pos, (name, value)) in headers.iter_mut().enumerate() {
+                        if name.eq_ignore_ascii_case(header_name.as_bytes()) {
+                            header_count += 1;
+                            if header_count == index {
+                                if !header_value.is_empty() {
+                                    *value = Cow::from(header_value.as_bytes().to_vec());
+                                } else {
+                                    headers.remove(pos);
+                                }
+                                break;
+                            }
+                        }
+                    }
+                } else {
+                    let mut header_pos = 0;
+                    if index > 0 {
+                        let mut header_count = 0;
+                        for (pos, (name, _)) in headers.iter().enumerate() {
+                            if name.eq_ignore_ascii_case(header_name.as_bytes()) {
+                                header_pos = pos;
+                                header_count += 1;
+                                if header_count == index {
+                                    break;
+                                }
+                            }
+                        }
+                    }
+
+                    headers.insert(
+                        header_pos,
+                        (
+                            Cow::from(header_name.as_bytes().to_vec()),
+                            Cow::from(header_value.as_bytes().to_vec()),
+                        ),
+                    );
+                }
+            }
+
+            // Write new headers
+            let mut new_message = Vec::with_capacity(
+                new_body.len()
+                    + message.raw_headers().len()
+                    + headers
+                        .iter()
+                        .map(|(h, v)| h.len() + v.len() + 4)
+                        .sum::<usize>(),
+            );
+            for (header, value) in headers {
+                new_message.extend_from_slice(header.as_ref());
+                if value.first().is_some_and(|c| c.is_ascii_whitespace()) {
+                    new_message.extend_from_slice(b":");
+                } else {
+                    new_message.extend_from_slice(b": ");
+                }
+                new_message.extend_from_slice(value.as_ref());
+                if value.last().is_none_or(|c| *c != b'\n') {
+                    new_message.extend_from_slice(b"\r\n");
+                }
+            }
+            new_message.extend_from_slice(b"\r\n");
+            new_message.extend(new_body);
+            Some(new_message)
+        } else {
+            let mut new_message = Vec::with_capacity(
+                new_body.len()
+                    + message.raw_headers().len()
+                    + header_changes
+                        .iter()
+                        .map(|(_, h, v, _)| h.len() + v.len() + 4)
+                        .sum::<usize>(),
+            );
+            for (_, header, value, _) in header_changes {
+                new_message.extend_from_slice(header.as_bytes());
+                new_message.extend_from_slice(b": ");
+                new_message.extend_from_slice(value.as_bytes());
+                if !value.ends_with('\n') {
+                    new_message.extend_from_slice(b"\r\n");
+                }
+            }
+            new_message.extend_from_slice(message.raw_headers());
+            new_message.extend(new_body);
+            Some(new_message)
+        }
+    }
+}
+
+impl Action {
+    fn assert_continue(self) -> Result<(), Rejection> {
+        match self {
+            Action::Continue | Action::Accept => Ok(()),
+            action => Err(Rejection::Action(action)),
+        }
+    }
+}
+
+impl From<Error> for Rejection {
+    fn from(err: Error) -> Self {
+        Rejection::Error(err)
+    }
+}
+
+fn strip_brackets(addr: &str) -> String {
+    let addr = addr.trim();
+    if let Some(addr) = addr.strip_prefix('<') {
+        if let Some((addr, _)) = addr.rsplit_once('>') {
+            addr.trim().into()
+        } else {
+            addr.trim().into()
+        }
+    } else {
+        addr.into()
+    }
+}

crates/smtp/src/inbound/milter/mod.rs

@@ -0,0 +1,488 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use self::receiver::Receiver;
+use common::config::smtp::session::MilterVersion;
+use registry::types::id::ObjectId;
+use serde::{Deserialize, Serialize};
+use std::{borrow::Cow, fmt::Display, net::IpAddr, time::Duration};
+use tokio::io::{AsyncRead, AsyncWrite};
+
+pub mod client;
+pub mod macros;
+pub mod message;
+pub mod protocol;
+pub mod receiver;
+
+pub struct MilterClient<T: AsyncRead + AsyncWrite> {
+    stream: T,
+    buf: Vec<u8>,
+    bytes_read: usize,
+    timeout_cmd: Duration,
+    timeout_data: Duration,
+    receiver: Receiver,
+    version: MilterVersion,
+    options: u32,
+    flags_actions: u32,
+    flags_protocol: u32,
+    id: ObjectId,
+    session_id: u64,
+}
+
+#[derive(Debug)]
+pub enum Error {
+    Io(std::io::Error),
+    FrameTooLarge(usize),
+    FrameInvalid(Vec<u8>),
+    Unexpected(Response),
+    Timeout,
+    TLSInvalidName,
+    Disconnected,
+}
+
+impl From<std::io::Error> for Error {
+    fn from(err: std::io::Error) -> Self {
+        Error::Io(err)
+    }
+}
+
+pub enum Command<'x> {
+    Abort,
+    Body {
+        value: &'x [u8],
+    },
+    EndOfBody,
+    Data,
+    Connect {
+        hostname: &'x [u8],
+        port: u16,
+        address: IpAddr,
+    },
+    Macro {
+        macros: Macros<'x>,
+    },
+    Header {
+        name: &'x [u8],
+        value: &'x [u8],
+    },
+    EndOfHeader,
+    Helo {
+        hostname: &'x [u8],
+    },
+    MailFrom {
+        sender: &'x [u8],
+        args: Option<Vec<&'x [u8]>>,
+    },
+    Rcpt {
+        recipient: &'x [u8],
+        args: Option<Vec<&'x [u8]>>,
+    },
+    OptionNegotiation(Options),
+    Quit,
+    QuitNewConnection,
+}
+
+#[derive(Debug)]
+pub enum Response {
+    Action(Action),
+    Modification(Modification),
+    Progress,
+    Skip,
+    SetSymbols,
+    OptionNegotiation(Options),
+}
+
+#[derive(Debug)]
+pub enum Action {
+    Accept,
+    Continue,
+    Discard,
+    Reject,
+    TempFail,
+    ReplyCode { code: [u8; 3], text: String },
+    Shutdown,
+    ConnectionFailure,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub enum Modification {
+    ChangeFrom {
+        sender: String,
+        args: String,
+    },
+    AddRcpt {
+        recipient: String,
+        args: String,
+    },
+    DeleteRcpt {
+        recipient: String,
+    },
+    ReplaceBody {
+        value: Vec<u8>,
+    },
+    AddHeader {
+        name: String,
+        value: String,
+    },
+    InsertHeader {
+        index: u32,
+        name: String,
+        value: String,
+    },
+    ChangeHeader {
+        index: u32,
+        name: String,
+        value: String,
+    },
+    Quarantine {
+        reason: String,
+    },
+}
+
+#[derive(Debug)]
+pub struct Options {
+    pub version: u32,
+    pub actions: u32,
+    pub protocol: u32,
+}
+
+#[derive(Default)]
+pub struct Macros<'x> {
+    cmdcode: u8,
+    macros: Vec<Macro<'x>>,
+}
+
+pub struct Macro<'x> {
+    name: &'x [u8],
+    value: Cow<'x, [u8]>,
+}
+
+pub const SMFIF_NONE: u32 = 0x00000000; /* no flags */
+pub const SMFIF_ADDHDRS: u32 = 0x00000001; /* filter may add headers */
+pub const SMFIF_CHGBODY: u32 = 0x00000002; /* filter may replace body */
+pub const SMFIF_MODBODY: u32 = SMFIF_CHGBODY; /* backwards compatible */
+pub const SMFIF_ADDRCPT: u32 = 0x00000004; /* filter may add recipients */
+pub const SMFIF_DELRCPT: u32 = 0x00000008; /* filter may delete recipients */
+pub const SMFIF_CHGHDRS: u32 = 0x00000010; /* filter may change/delete headers */
+pub const SMFIF_QUARANTINE: u32 = 0x00000020; /* filter may quarantine envelope */
+pub const SMFIF_CHGFROM: u32 = 0x00000040; /* filter may change "from" (envelope sender) */
+pub const SMFIF_ADDRCPT_PAR: u32 = 0x00000080; /* add recipients incl. args */
+pub const SMFIF_SETSYMLIST: u32 = 0x00000100; /* filter can send set of symbols (macros) that it wants */
+
+pub const SMFIP_NOCONNECT: u32 = 0x00000001; /* MTA should not send connect info */
+pub const SMFIP_NOHELO: u32 = 0x00000002; /* MTA should not send HELO info */
+pub const SMFIP_NOMAIL: u32 = 0x00000004; /* MTA should not send MAIL info */
+pub const SMFIP_NORCPT: u32 = 0x00000008; /* MTA should not send RCPT info */
+pub const SMFIP_NOBODY: u32 = 0x00000010; /* MTA should not send body */
+pub const SMFIP_NOHDRS: u32 = 0x00000020; /* MTA should not send headers */
+pub const SMFIP_NOEOH: u32 = 0x00000040; /* MTA should not send EOH */
+pub const SMFIP_NR_HDR: u32 = 0x00000080; /* No reply for headers */
+pub const SMFIP_NOHREPL: u32 = SMFIP_NR_HDR; /* No reply for headers */
+pub const SMFIP_NOUNKNOWN: u32 = 0x00000100; /* MTA should not send unknown commands */
+pub const SMFIP_NODATA: u32 = 0x00000200; /* MTA should not send DATA */
+pub const SMFIP_SKIP: u32 = 0x00000400; /* MTA understands SMFIS_SKIP */
+pub const SMFIP_RCPT_REJ: u32 = 0x00000800; /* MTA should also send rejected RCPTs */
+pub const SMFIP_NR_CONN: u32 = 0x00001000; /* No reply for connect */
+pub const SMFIP_NR_HELO: u32 = 0x00002000; /* No reply for HELO */
+pub const SMFIP_NR_MAIL: u32 = 0x00004000; /* No reply for MAIL */
+pub const SMFIP_NR_RCPT: u32 = 0x00008000; /* No reply for RCPT */
+pub const SMFIP_NR_DATA: u32 = 0x00010000; /* No reply for DATA */
+pub const SMFIP_NR_UNKN: u32 = 0x00020000; /* No reply for UNKN */
+pub const SMFIP_NR_EOH: u32 = 0x00040000; /* No reply for eoh */
+pub const SMFIP_NR_BODY: u32 = 0x00080000; /* No reply for body chunk */
+pub const SMFIP_HDR_LEADSPC: u32 = 0x00100000; /* header value leading space */
+pub const SMFIP_MDS_256K: u32 = 0x10000000; /* MILTER_MAX_DATA_SIZE=256K */
+pub const SMFIP_MDS_1M: u32 = 0x20000000; /* MILTER_MAX_DATA_SIZE=1M */
+
+pub type Result<T> = std::result::Result<T, Error>;
+
+impl Display for Command<'_> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Command::Abort => write!(f, "ABORT"),
+            Command::Body { value } => write!(f, "BODY [{} bytes]", value.len()),
+            Command::EndOfBody => write!(f, "EOB"),
+            Command::Connect {
+                hostname,
+                port,
+                address,
+            } => write!(
+                f,
+                "CONNECT (host: {:?}, port: {}, address: {})",
+                std::str::from_utf8(hostname).unwrap_or_default(),
+                port,
+                address
+            ),
+            Command::Macro { macros } => {
+                write!(f, "MACRO (code: {}, params: ", macros.cmdcode)?;
+                for macro_ in &macros.macros {
+                    write!(
+                        f,
+                        "({:?}, {:?})",
+                        std::str::from_utf8(macro_.name).unwrap_or_default(),
+                        std::str::from_utf8(macro_.value.as_ref()).unwrap_or_default()
+                    )?;
+                }
+                write!(f, ")")
+            }
+            Command::Header { name, value } => {
+                write!(
+                    f,
+                    "HEADER ({}: {:?})",
+                    std::str::from_utf8(name).unwrap_or_default(),
+                    std::str::from_utf8(value).unwrap_or_default()
+                )
+            }
+            Command::EndOfHeader => write!(f, "EOH"),
+            Command::Helo { hostname } => write!(
+                f,
+                "HELO {:?}",
+                std::str::from_utf8(hostname).unwrap_or_default()
+            ),
+            Command::MailFrom { sender, args } => {
+                write!(
+                    f,
+                    "MAIL (from: {}, params: ",
+                    std::str::from_utf8(sender).unwrap_or_default()
+                )?;
+                if let Some(args) = args {
+                    for arg in args {
+                        write!(f, " {}", std::str::from_utf8(arg).unwrap_or_default())?;
+                    }
+                }
+                write!(f, ")")
+            }
+            Command::Rcpt { recipient, args } => {
+                write!(
+                    f,
+                    "RCPT (to: {}, params: ",
+                    std::str::from_utf8(recipient).unwrap_or_default()
+                )?;
+                if let Some(args) = args {
+                    for arg in args {
+                        write!(f, " {}", std::str::from_utf8(arg).unwrap_or_default())?;
+                    }
+                }
+                write!(f, ")")
+            }
+            Command::OptionNegotiation(opt) => write!(f, "OPTNEG ({})", opt),
+            Command::Quit => write!(f, "QUIT"),
+            Command::Data => write!(f, "DATA"),
+            Command::QuitNewConnection => write!(f, "QUIT_NC"),
+        }
+    }
+}
+
+impl Display for Response {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Response::Action(action) => write!(f, "ACTION ({})", action),
+            Response::Modification(modification) => write!(f, "MODIFICATION ({})", modification),
+            Response::Progress => write!(f, "PROGRESS"),
+            Response::OptionNegotiation(opt) => write!(f, "OPTNEG ({})", opt),
+            Response::Skip => write!(f, "SKIP"),
+            Response::SetSymbols => write!(f, "SET_SYMBOLS"),
+        }
+    }
+}
+
+impl Display for Action {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Action::Accept => write!(f, "ACCEPT"),
+            Action::Continue => write!(f, "CONTINUE"),
+            Action::Discard => write!(f, "DISCARD"),
+            Action::Reject => write!(f, "REJECT"),
+            Action::TempFail => write!(f, "TEMPFAIL"),
+            Action::ReplyCode { code, text } => {
+                write!(f, "REPLYCODE (code: {:?}, text: {})", code, text)
+            }
+            Action::Shutdown => write!(f, "SHUTDOWN"),
+            Action::ConnectionFailure => write!(f, "CONN_FAIL"),
+        }
+    }
+}
+
+impl Display for Modification {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Modification::AddRcpt { recipient, args } => {
+                write!(f, "ADD_RCPT (recipient: {}, args: {})", recipient, args)
+            }
+            Modification::DeleteRcpt { recipient } => {
+                write!(f, "DEL_RCPT (recipient: {})", recipient)
+            }
+            Modification::ReplaceBody { value } => {
+                write!(f, "REPLACE_BODY ({} bytes)", value.len())
+            }
+            Modification::AddHeader { name, value } => {
+                write!(f, "ADD_HEADER ({}: {})", name, value)
+            }
+            Modification::ChangeHeader { index, name, value } => {
+                write!(f, "CHANGE_HEADER (index: {}, {}: {})", index, name, value)
+            }
+            Modification::Quarantine { reason } => write!(f, "QUARANTINE ({})", reason),
+            Modification::ChangeFrom { sender, args } => {
+                write!(f, "CHANGE_FROM (<{}> {})", sender, args)
+            }
+            Modification::InsertHeader { index, name, value } => {
+                write!(f, "INSERT_HEADER (index: {}, {}: {})", index, name, value)
+            }
+        }
+    }
+}
+
+impl Display for Options {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "version: {}, actions: [", self.version,)?;
+
+        if self.actions & SMFIF_ADDHDRS != 0 {
+            write!(f, "ADDHDRS ")?;
+        }
+        if self.actions & SMFIF_CHGBODY != 0 {
+            write!(f, "CHGBODY ")?;
+        }
+        if self.actions & SMFIF_CHGHDRS != 0 {
+            write!(f, "CHGHDRS ")?;
+        }
+        if self.actions & SMFIF_ADDRCPT != 0 {
+            write!(f, "ADDRCPT ")?;
+        }
+        if self.actions & SMFIF_DELRCPT != 0 {
+            write!(f, "DELRCPT ")?;
+        }
+        if self.actions & SMFIF_CHGFROM != 0 {
+            write!(f, "CHGFROM ")?;
+        }
+        if self.actions & SMFIF_QUARANTINE != 0 {
+            write!(f, "QUARANTINE ")?;
+        }
+        if self.actions & SMFIF_CHGFROM != 0 {
+            write!(f, "CHGFROM ")?;
+        }
+        if self.actions & SMFIF_ADDRCPT_PAR != 0 {
+            write!(f, "ADDRCPT_PAR ")?;
+        }
+        if self.actions & SMFIF_SETSYMLIST != 0 {
+            write!(f, "SETSYMLIST ")?;
+        }
+        write!(f, "], options: [",)?;
+
+        if self.protocol & SMFIP_NOCONNECT != 0 {
+            write!(f, "NOCONNECT ")?;
+        }
+
+        if self.protocol & SMFIP_NOHELO != 0 {
+            write!(f, "NOHELO ")?;
+        }
+
+        if self.protocol & SMFIP_NOMAIL != 0 {
+            write!(f, "NOMAIL ")?;
+        }
+
+        if self.protocol & SMFIP_NORCPT != 0 {
+            write!(f, "NORCPT ")?;
+        }
+
+        if self.protocol & SMFIP_NOBODY != 0 {
+            write!(f, "NOBODY ")?;
+        }
+
+        if self.protocol & SMFIP_NOHDRS != 0 {
+            write!(f, "NOHDRS ")?;
+        }
+
+        if self.protocol & SMFIP_NOEOH != 0 {
+            write!(f, "NOEOH ")?;
+        }
+
+        if self.protocol & SMFIP_NR_HDR != 0 {
+            write!(f, "NR_HDR ")?;
+        }
+
+        if self.protocol & SMFIP_NOUNKNOWN != 0 {
+            write!(f, "NOUNKNOWN ")?;
+        }
+
+        if self.protocol & SMFIP_NODATA != 0 {
+            write!(f, "NODATA ")?;
+        }
+
+        if self.protocol & SMFIP_SKIP != 0 {
+            write!(f, "SKIP ")?;
+        }
+
+        if self.protocol & SMFIP_RCPT_REJ != 0 {
+            write!(f, "RCPT_REJ ")?;
+        }
+
+        if self.protocol & SMFIP_NR_CONN != 0 {
+            write!(f, "NR_CONN ")?;
+        }
+
+        if self.protocol & SMFIP_NR_HELO != 0 {
+            write!(f, "NR_HELO ")?;
+        }
+
+        if self.protocol & SMFIP_NR_MAIL != 0 {
+            write!(f, "NR_MAIL ")?;
+        }
+
+        if self.protocol & SMFIP_NR_RCPT != 0 {
+            write!(f, "NR_RCPT ")?;
+        }
+
+        if self.protocol & SMFIP_NR_DATA != 0 {
+            write!(f, "NR_DATA ")?;
+        }
+
+        if self.protocol & SMFIP_NR_UNKN != 0 {
+            write!(f, "NR_UNKN ")?;
+        }
+
+        if self.protocol & SMFIP_NR_EOH != 0 {
+            write!(f, "NR_EOH ")?;
+        }
+
+        if self.protocol & SMFIP_NR_BODY != 0 {
+            write!(f, "NR_BODY ")?;
+        }
+
+        if self.protocol & SMFIP_HDR_LEADSPC != 0 {
+            write!(f, "HDR_LEADSPC ")?;
+        }
+
+        if self.protocol & SMFIP_MDS_256K != 0 {
+            write!(f, "MDS_256K ")?;
+        }
+
+        if self.protocol & SMFIP_MDS_1M != 0 {
+            write!(f, "MDS_1M ")?;
+        }
+
+        write!(f, "]")
+    }
+}
+
+impl Display for Error {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Error::Io(err) => write!(f, "IO error: {}", err),
+            Error::FrameTooLarge(size) => {
+                write!(f, "Milter response of {} bytes is too large.", size)
+            }
+            Error::FrameInvalid(frame) => write!(
+                f,
+                "Invalid milter response: {:?}",
+                frame.get(0..100).unwrap_or(frame.as_ref())
+            ),
+            Error::Unexpected(response) => write!(f, "Unexpected response: {}", response),
+            Error::Timeout => write!(f, "Connection timed out"),
+            Error::TLSInvalidName => write!(f, "Invalid TLS name"),
+            Error::Disconnected => write!(f, "Disconnected unexpectedly"),
+        }
+    }
+}

crates/smtp/src/inbound/milter/protocol.rs

@@ -0,0 +1,532 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use std::net::IpAddr;
+
+use crate::inbound::milter::Action;
+
+use super::{Command, Error, Modification, Options, Response};
+
+pub const SMFIR_ADDRCPT: u8 = b'+'; /* add recipient */
+pub const SMFIR_DELRCPT: u8 = b'-'; /* remove recipient */
+pub const SMFIR_ADDRCPT_PAR: u8 = b'2'; /* add recipient (incl. ESMTP args) */
+pub const SMFIR_SHUTDOWN: u8 = b'4'; /* 421: shutdown (internal to MTA) */
+pub const SMFIR_ACCEPT: u8 = b'a'; /* accept */
+pub const SMFIR_REPLBODY: u8 = b'b'; /* replace body (chunk) */
+pub const SMFIR_CONTINUE: u8 = b'c'; /* continue */
+pub const SMFIR_DISCARD: u8 = b'd'; /* discard */
+pub const SMFIR_CHGFROM: u8 = b'e'; /* change envelope sender (from) */
+pub const SMFIR_CONN_FAIL: u8 = b'f'; /* cause a connection failure */
+pub const SMFIR_ADDHEADER: u8 = b'h'; /* add header */
+pub const SMFIR_INSHEADER: u8 = b'i'; /* insert header */
+pub const SMFIR_SETSYMLIST: u8 = b'l'; /* set list of symbols (macros) */
+pub const SMFIR_CHGHEADER: u8 = b'm'; /* change header */
+pub const SMFIR_PROGRESS: u8 = b'p'; /* progress */
+pub const SMFIR_QUARANTINE: u8 = b'q'; /* quarantine */
+pub const SMFIR_REJECT: u8 = b'r'; /* reject */
+pub const SMFIR_SKIP: u8 = b's'; /* skip */
+pub const SMFIR_TEMPFAIL: u8 = b't'; /* tempfail */
+pub const SMFIR_REPLYCODE: u8 = b'y'; /* reply code etc */
+
+pub const SMFIC_ABORT: u8 = b'A'; /* Abort */
+pub const SMFIC_BODY: u8 = b'B'; /* Body chunk */
+pub const SMFIC_CONNECT: u8 = b'C'; /* Connection information */
+pub const SMFIC_MACRO: u8 = b'D'; /* Define macro */
+pub const SMFIC_BODYEOB: u8 = b'E'; /* final body chunk (End) */
+pub const SMFIC_HELO: u8 = b'H'; /* HELO/EHLO */
+pub const SMFIC_QUIT_NC: u8 = b'K'; /* QUIT but new connection follows */
+pub const SMFIC_HEADER: u8 = b'L'; /* Header */
+pub const SMFIC_MAIL: u8 = b'M'; /* MAIL from */
+pub const SMFIC_EOH: u8 = b'N'; /* EOH */
+pub const SMFIC_OPTNEG: u8 = b'O'; /* Option negotiation */
+pub const SMFIC_QUIT: u8 = b'Q'; /* QUIT */
+pub const SMFIC_RCPT: u8 = b'R'; /* RCPT to */
+pub const SMFIC_DATA: u8 = b'T'; /* DATA */
+pub const SMFIC_UNKNOWN: u8 = b'U'; /* Any unknown command */
+
+impl Command<'_> {
+    fn build(command: u8, len: u32) -> Vec<u8> {
+        let mut buf = Vec::with_capacity(len as usize + 1 + std::mem::size_of::<u32>());
+        buf.extend_from_slice((len + 1).to_be_bytes().as_slice());
+        buf.push(command);
+        buf
+    }
+
+    pub fn serialize(self) -> Vec<u8> {
+        match self {
+            Command::Abort => Command::build(SMFIC_ABORT, 0),
+            Command::Body { value } => {
+                let mut buf = Command::build(SMFIC_BODY, value.len() as u32);
+                buf.extend(value);
+                buf
+            }
+            Command::EndOfBody => Command::build(SMFIC_BODYEOB, 0),
+            Command::Connect {
+                hostname,
+                port,
+                address,
+            } => {
+                /*
+
+                char	hostname[]	Hostname, NUL terminated
+                char	family		Protocol family (see below)
+                uint16	port		Port number (SMFIA_INET or SMFIA_INET6 only)
+                char	address[]	IP address (ASCII) or unix socket path, NUL terminated
+
+                */
+
+                let (address, family) = match address {
+                    IpAddr::V4(address) => (address.to_string(), b'4'),
+                    IpAddr::V6(address) => (address.to_string(), b'6'),
+                };
+
+                let mut buf = Command::build(
+                    SMFIC_CONNECT,
+                    hostname.len() as u32 // hostname
+                        + 1 // NUL
+                        + 1 // family
+                        + std::mem::size_of::<u16>() as u32 // port
+                        + address.len() as u32 // address
+                        + 1, // NUL
+                );
+                buf.extend(hostname);
+                buf.push(0x00);
+                buf.push(family);
+                buf.extend(port.to_be_bytes().as_slice());
+                buf.extend(address.as_bytes());
+                buf.push(0x00);
+                buf
+            }
+            Command::Macro { macros } => {
+                let mut buf = Command::build(
+                    SMFIC_MACRO,
+                    macros.macros.iter().fold(1, |acc, macro_| {
+                        acc + macro_.name.len() as u32 + 1 + macro_.value.len() as u32 + 1
+                    }),
+                );
+                buf.push(macros.cmdcode);
+                for macro_ in macros.macros {
+                    buf.extend(macro_.name);
+                    buf.push(0x00);
+                    buf.extend(macro_.value.as_ref());
+                    buf.push(0x00);
+                }
+                buf
+            }
+            Command::Header { name, value } => {
+                let mut buf =
+                    Command::build(SMFIC_HEADER, name.len() as u32 + 1 + value.len() as u32 + 1);
+                buf.extend(name);
+                buf.push(0x00);
+                buf.extend(value);
+                buf.push(0x00);
+                buf
+            }
+            Command::EndOfHeader => Command::build(SMFIC_EOH, 0),
+            Command::Helo { hostname } => {
+                let mut buf = Command::build(SMFIC_HELO, hostname.len() as u32 + 1);
+                buf.extend(hostname);
+                buf.push(0x00);
+                buf
+            }
+            Command::MailFrom { sender, args } => {
+                let mut buf = Command::build(
+                    SMFIC_MAIL,
+                    sender.len() as u32 // sender
+                        + 1 // NUL
+                        + args.as_ref().map_or(0, |args| args.iter().fold(0, |acc, arg| acc + arg.len() as u32) + 1), // args
+                );
+                buf.extend(sender);
+                buf.push(0x00);
+                if let Some(args) = args {
+                    for arg in args {
+                        buf.extend(arg);
+                        buf.push(0x00);
+                    }
+                }
+                buf
+            }
+            Command::Rcpt { recipient, args } => {
+                let mut buf = Command::build(
+                    SMFIC_RCPT,
+                    recipient.len() as u32 // recipient
+                        + 1 // NUL
+                        + args.as_ref().map_or(0, |args| args.iter().fold(0, |acc, arg| acc + arg.len() as u32) + 1), // args
+                );
+                buf.extend(recipient);
+                buf.push(0x00);
+                if let Some(args) = args {
+                    for arg in args {
+                        buf.extend(arg);
+                        buf.push(0x00);
+                    }
+                }
+                buf
+            }
+            Command::OptionNegotiation(opt) => {
+                let mut buf = Command::build(SMFIC_OPTNEG, 3 * std::mem::size_of::<u32>() as u32);
+                buf.extend(opt.version.to_be_bytes().as_slice());
+                buf.extend(opt.actions.to_be_bytes().as_slice());
+                buf.extend(opt.protocol.to_be_bytes().as_slice());
+                buf
+            }
+            Command::Quit => Command::build(SMFIC_QUIT, 0),
+
+            // Version 6
+            Command::Data => Command::build(SMFIC_DATA, 0),
+            Command::QuitNewConnection => Command::build(SMFIC_QUIT_NC, 0),
+        }
+    }
+
+    #[cfg(feature = "test_mode")]
+    pub fn deserialize(bytes: &[u8]) -> Command<'_> {
+        let mut reader = PacketReader::new(bytes);
+        match reader.byte() {
+            SMFIC_ABORT => Command::Abort,
+            SMFIC_BODY => Command::Body { value: &bytes[1..] },
+            SMFIC_BODYEOB => Command::EndOfBody,
+            SMFIC_CONNECT => {
+                let hostname = reader.read_nul_terminated().unwrap();
+                let family = reader.byte();
+                let port = reader.read_u16();
+                let address = std::str::from_utf8(reader.read_nul_terminated().unwrap()).unwrap();
+                Command::Connect {
+                    hostname,
+                    port,
+                    address: match family {
+                        b'4' => IpAddr::V4(address.parse().unwrap()),
+                        b'6' => IpAddr::V6(address.parse().unwrap()),
+                        _ => unreachable!(),
+                    },
+                }
+            }
+            SMFIC_MACRO => {
+                let cmdcode = reader.byte();
+                let mut macros = Vec::new();
+                while let Some(name) = reader.read_nul_terminated() {
+                    let value = reader.read_nul_terminated().unwrap();
+                    macros.push(super::Macro {
+                        name,
+                        value: value.into(),
+                    });
+                }
+                Command::Macro {
+                    macros: super::Macros { cmdcode, macros },
+                }
+            }
+            SMFIC_HEADER => {
+                let name = reader.read_nul_terminated().unwrap();
+                let value = reader.read_nul_terminated().unwrap();
+                Command::Header { name, value }
+            }
+            SMFIC_EOH => Command::EndOfHeader,
+            SMFIC_HELO => {
+                let hostname = reader.read_nul_terminated().unwrap();
+                Command::Helo { hostname }
+            }
+            SMFIC_MAIL => {
+                let sender = reader.read_nul_terminated().unwrap();
+                let mut args = Vec::new();
+                while let Some(arg) = reader.read_nul_terminated() {
+                    args.push(arg);
+                }
+                Command::MailFrom {
+                    sender,
+                    args: Some(args),
+                }
+            }
+            SMFIC_RCPT => {
+                let recipient = reader.read_nul_terminated().unwrap();
+                let mut args = Vec::new();
+                while let Some(arg) = reader.read_nul_terminated() {
+                    args.push(arg);
+                }
+                Command::Rcpt {
+                    recipient,
+                    args: Some(args),
+                }
+            }
+            SMFIC_OPTNEG => Command::OptionNegotiation(super::Options {
+                version: reader.read_u32(),
+                actions: reader.read_u32(),
+                protocol: reader.read_u32(),
+            }),
+            SMFIC_QUIT => Command::Quit,
+            SMFIC_DATA => Command::Data,
+            SMFIC_QUIT_NC => Command::QuitNewConnection,
+            c => panic!("Unknown command: {}", char::from(c)),
+        }
+    }
+}
+
+impl Response {
+    pub fn deserialize(bytes: &[u8]) -> Option<Self> {
+        let frame_len = bytes.len().saturating_sub(1);
+        let mut bytes = bytes.iter();
+        match *bytes.next()? {
+            SMFIR_ADDRCPT => Response::Modification(Modification::AddRcpt {
+                recipient: read_nul_terminated(&mut bytes, frame_len)?,
+                args: String::new(),
+            }),
+            SMFIR_DELRCPT => Response::Modification(Modification::DeleteRcpt {
+                recipient: read_nul_terminated(&mut bytes, frame_len)?,
+            }),
+            SMFIR_ACCEPT => Response::Action(Action::Accept),
+            SMFIR_REPLBODY => {
+                let mut body = Vec::with_capacity(frame_len);
+                body.extend(bytes);
+                Response::Modification(Modification::ReplaceBody { value: body })
+            }
+            SMFIR_CONTINUE => Response::Action(Action::Continue),
+            SMFIR_DISCARD => Response::Action(Action::Discard),
+            SMFIR_ADDHEADER => Response::Modification(Modification::AddHeader {
+                name: read_nul_terminated(&mut bytes, 16)?,
+                value: read_nul_terminated(&mut bytes, frame_len)?,
+            }),
+            SMFIR_CHGHEADER => Response::Modification(Modification::ChangeHeader {
+                index: read_u32(&mut bytes)?,
+                name: read_nul_terminated(&mut bytes, 16)?,
+                value: read_nul_terminated(&mut bytes, frame_len)?,
+            }),
+            SMFIR_PROGRESS => Response::Progress,
+            SMFIR_QUARANTINE => Response::Modification(Modification::Quarantine {
+                reason: read_nul_terminated(&mut bytes, frame_len)?,
+            }),
+            SMFIR_REJECT => Response::Action(Action::Reject),
+            SMFIR_TEMPFAIL => Response::Action(Action::TempFail),
+            SMFIR_REPLYCODE => {
+                let code = [*bytes.next()?, *bytes.next()?, *bytes.next()?];
+                bytes.next()?; // Space
+                Response::Action(Action::ReplyCode {
+                    code,
+                    text: read_nul_terminated(&mut bytes, frame_len)?,
+                })
+            }
+            SMFIC_OPTNEG => Response::OptionNegotiation(Options {
+                version: read_u32(&mut bytes)?,
+                actions: read_u32(&mut bytes)?,
+                protocol: read_u32(&mut bytes)?,
+            }),
+
+            // V6
+            SMFIR_ADDRCPT_PAR => Response::Modification(Modification::AddRcpt {
+                recipient: read_nul_terminated(&mut bytes, frame_len)?,
+                args: read_nul_terminated(&mut bytes, frame_len)?,
+            }),
+            SMFIR_CHGFROM => Response::Modification(Modification::ChangeFrom {
+                sender: read_nul_terminated(&mut bytes, frame_len)?,
+                args: read_nul_terminated(&mut bytes, frame_len)?,
+            }),
+            SMFIR_SKIP => Response::Skip,
+            SMFIR_SETSYMLIST => Response::SetSymbols,
+            SMFIR_SHUTDOWN => Response::Action(Action::Shutdown),
+            SMFIR_CONN_FAIL => Response::Action(Action::ConnectionFailure),
+            SMFIR_INSHEADER => Response::Modification(Modification::InsertHeader {
+                index: read_u32(&mut bytes)?,
+                name: read_nul_terminated(&mut bytes, 16)?,
+                value: read_nul_terminated(&mut bytes, frame_len)?,
+            }),
+            _ => return None,
+        }
+        .into()
+    }
+
+    pub fn can_continue(&self) -> bool {
+        matches!(
+            self,
+            Response::Progress | Response::Action(Action::Accept | Action::Continue)
+        )
+    }
+
+    pub fn into_action(self) -> super::Result<Action> {
+        match self {
+            Response::Action(action) => Ok(action),
+            response => Err(Error::Unexpected(response)),
+        }
+    }
+
+    #[cfg(feature = "test_mode")]
+    pub fn serialize(&self) -> Vec<u8> {
+        match self {
+            Response::Action(action) => match action {
+                Action::Accept => Command::build(SMFIR_ACCEPT, 0),
+                Action::Continue => Command::build(SMFIR_CONTINUE, 0),
+                Action::Discard => Command::build(SMFIR_DISCARD, 0),
+                Action::Reject => Command::build(SMFIR_REJECT, 0),
+                Action::TempFail => Command::build(SMFIR_TEMPFAIL, 0),
+                Action::ReplyCode { code, text } => {
+                    let mut buf = Command::build(SMFIR_REPLYCODE, text.len() as u32 + 4 + 1);
+                    buf.extend(code);
+                    buf.push(b' ');
+                    buf.extend(text.as_bytes());
+                    buf.push(0x00);
+                    buf
+                }
+                Action::Shutdown => Command::build(SMFIR_SHUTDOWN, 0),
+                Action::ConnectionFailure => Command::build(SMFIR_CONN_FAIL, 0),
+            },
+            Response::Modification(modif) => match modif {
+                Modification::ChangeFrom { sender, args } => {
+                    let mut buf =
+                        Command::build(SMFIR_CHGFROM, sender.len() as u32 + args.len() as u32 + 2);
+                    buf.extend(sender.as_bytes());
+                    buf.push(0x00);
+                    buf.extend(args.as_bytes());
+                    buf.push(0x00);
+                    buf
+                }
+                Modification::AddRcpt { recipient, args } => {
+                    let mut buf = Command::build(
+                        SMFIR_ADDRCPT_PAR,
+                        recipient.len() as u32 + args.len() as u32 + 2,
+                    );
+                    buf.extend(recipient.as_bytes());
+                    buf.push(0x00);
+                    buf.extend(args.as_bytes());
+                    buf.push(0x00);
+                    buf
+                }
+                Modification::DeleteRcpt { recipient } => {
+                    let mut buf = Command::build(SMFIR_DELRCPT, recipient.len() as u32 + 1);
+                    buf.extend(recipient.as_bytes());
+                    buf.push(0x00);
+                    buf
+                }
+                Modification::ReplaceBody { value } => {
+                    let mut buf = Command::build(SMFIR_REPLBODY, value.len() as u32);
+                    buf.extend(value);
+                    buf
+                }
+                Modification::AddHeader { name, value } => {
+                    let mut buf =
+                        Command::build(SMFIR_ADDHEADER, name.len() as u32 + value.len() as u32 + 2);
+                    buf.extend(name.as_bytes());
+                    buf.push(0x00);
+                    buf.extend(value.as_bytes());
+                    buf.push(0x00);
+                    buf
+                }
+                Modification::InsertHeader { index, name, value } => {
+                    let mut buf = Command::build(
+                        SMFIR_INSHEADER,
+                        name.len() as u32
+                            + value.len() as u32
+                            + std::mem::size_of::<u32>() as u32
+                            + 2,
+                    );
+                    buf.extend(index.to_be_bytes().as_slice());
+                    buf.extend(name.as_bytes());
+                    buf.push(0x00);
+                    buf.extend(value.as_bytes());
+                    buf.push(0x00);
+                    buf
+                }
+                Modification::ChangeHeader { index, name, value } => {
+                    let mut buf = Command::build(
+                        SMFIR_CHGHEADER,
+                        name.len() as u32
+                            + value.len() as u32
+                            + std::mem::size_of::<u32>() as u32
+                            + 2,
+                    );
+                    buf.extend(index.to_be_bytes().as_slice());
+                    buf.extend(name.as_bytes());
+                    buf.push(0x00);
+                    buf.extend(value.as_bytes());
+                    buf.push(0x00);
+                    buf
+                }
+                Modification::Quarantine { reason } => {
+                    let mut buf = Command::build(SMFIR_QUARANTINE, reason.len() as u32 + 1);
+                    buf.extend(reason.as_bytes());
+                    buf.push(0x00);
+                    buf
+                }
+            },
+            Response::Progress => Command::build(SMFIR_PROGRESS, 0),
+            Response::Skip => Command::build(SMFIR_SKIP, 0),
+            Response::SetSymbols => Command::build(SMFIR_SETSYMLIST, 0),
+            Response::OptionNegotiation(opt) => {
+                let mut buf = Command::build(SMFIC_OPTNEG, 3 * std::mem::size_of::<u32>() as u32);
+                buf.extend(opt.version.to_be_bytes().as_slice());
+                buf.extend(opt.actions.to_be_bytes().as_slice());
+                buf.extend(opt.protocol.to_be_bytes().as_slice());
+                buf
+            }
+        }
+    }
+}
+
+fn read_nul_terminated(bytes: &mut std::slice::Iter<u8>, expected_len: usize) -> Option<String> {
+    let mut buf = Vec::with_capacity(expected_len);
+    loop {
+        match bytes.next()? {
+            0x00 => break,
+            byte => buf.push(*byte),
+        }
+    }
+    String::from_utf8(buf).ok()
+}
+
+fn read_u32(bytes: &mut std::slice::Iter<u8>) -> Option<u32> {
+    let mut buf = [0u8; 4];
+    for byte in buf.iter_mut() {
+        *byte = *bytes.next()?;
+    }
+    Some(u32::from_be_bytes(buf))
+}
+
+#[cfg(feature = "test_mode")]
+pub struct PacketReader<'x> {
+    bytes: &'x [u8],
+    iter: std::iter::Enumerate<std::slice::Iter<'x, u8>>,
+}
+
+#[cfg(feature = "test_mode")]
+impl<'x> PacketReader<'x> {
+    pub fn new(bytes: &'x [u8]) -> PacketReader<'x> {
+        Self {
+            bytes,
+            iter: bytes.iter().enumerate(),
+        }
+    }
+
+    pub fn byte(&mut self) -> u8 {
+        *self.iter.next().unwrap().1
+    }
+
+    pub fn read_nul_terminated(&mut self) -> Option<&'x [u8]> {
+        let (start_pos, ch) = self.iter.next()?;
+        let mut end_pos = start_pos;
+
+        if *ch != 0x00 {
+            loop {
+                match self.iter.next().unwrap().1 {
+                    0x00 => break,
+                    _ => end_pos += 1,
+                }
+            }
+        }
+
+        Some(&self.bytes[start_pos..end_pos + 1])
+    }
+
+    pub fn read_u32(&mut self) -> u32 {
+        let mut buf = [0u8; 4];
+        for byte in buf.iter_mut() {
+            *byte = self.byte();
+        }
+        u32::from_be_bytes(buf)
+    }
+
+    pub fn read_u16(&mut self) -> u16 {
+        let mut buf = [0u8; 2];
+        for byte in buf.iter_mut() {
+            *byte = self.byte();
+        }
+        u16::from_be_bytes(buf)
+    }
+}

crates/smtp/src/inbound/milter/receiver.rs

@@ -0,0 +1,110 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use std::borrow::Cow;
+
+enum State {
+    Len {
+        buf: [u8; std::mem::size_of::<u32>()],
+        bytes_read: usize,
+    },
+    Frame {
+        buf: Vec<u8>,
+        frame_len: usize,
+    },
+}
+
+pub struct Receiver {
+    packet_pos: usize,
+    state: State,
+    max_frame_len: usize,
+}
+
+pub enum FrameResult<'x> {
+    Frame(Cow<'x, [u8]>),
+    Incomplete,
+    TooLarge(usize),
+}
+
+impl Default for State {
+    fn default() -> Self {
+        State::Len {
+            buf: [0; std::mem::size_of::<u32>()],
+            bytes_read: 0,
+        }
+    }
+}
+
+impl Receiver {
+    pub fn with_max_frame_len(max_frame_len: usize) -> Self {
+        Receiver {
+            packet_pos: 0,
+            state: State::default(),
+            max_frame_len,
+        }
+    }
+
+    pub fn read_frame<'x>(&mut self, packet: &'x [u8]) -> FrameResult<'x> {
+        if !packet.is_empty() {
+            match &mut self.state {
+                State::Len { buf, bytes_read } => {
+                    while *bytes_read < std::mem::size_of::<u32>() {
+                        if let Some(byte) = packet.get(self.packet_pos) {
+                            buf[*bytes_read] = *byte;
+                            *bytes_read += 1;
+                            self.packet_pos += 1;
+                        } else {
+                            self.packet_pos = 0;
+                            return FrameResult::Incomplete;
+                        }
+                    }
+                    let length = u32::from_be_bytes(*buf) as usize;
+                    if length <= self.max_frame_len {
+                        if let Some(frame) = packet.get(self.packet_pos..self.packet_pos + length) {
+                            self.packet_pos += length;
+                            self.state = State::default();
+                            FrameResult::Frame(frame.into())
+                        } else {
+                            let mut buf = Vec::with_capacity(length);
+                            if let Some(bytes_available) = packet.get(self.packet_pos..) {
+                                buf.extend(bytes_available);
+                            }
+                            self.state = State::Frame {
+                                buf,
+                                frame_len: length,
+                            };
+                            self.packet_pos = 0;
+                            FrameResult::Incomplete
+                        }
+                    } else {
+                        FrameResult::TooLarge(length)
+                    }
+                }
+                State::Frame { buf, frame_len } => {
+                    let bytes_pending = *frame_len - buf.len();
+                    if let Some(bytes) =
+                        packet.get(self.packet_pos..self.packet_pos + bytes_pending)
+                    {
+                        let mut buf = std::mem::take(buf);
+                        buf.extend(bytes);
+                        self.packet_pos += bytes_pending;
+                        self.state = State::default();
+                        FrameResult::Frame(buf.into())
+                    } else if let Some(bytes_available) = packet.get(self.packet_pos..) {
+                        buf.extend(bytes_available);
+                        self.packet_pos = 0;
+                        FrameResult::Incomplete
+                    } else {
+                        self.packet_pos = 0;
+                        FrameResult::Incomplete
+                    }
+                }
+            }
+        } else {
+            FrameResult::Incomplete
+        }
+    }
+}

crates/smtp/src/inbound/mod.rs

@@ -0,0 +1,143 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use mail_auth::{DkimResult, DmarcResult, IprevResult, SpfResult, dmarc::Policy};
+use std::borrow::Cow;
+
+pub mod auth;
+pub mod data;
+pub mod dkim;
+pub mod ehlo;
+pub mod hooks;
+pub mod mail;
+pub mod milter;
+pub mod rcpt;
+pub mod session;
+pub mod spam;
+pub mod spawn;
+pub mod vrfy;
+
+#[derive(Debug, Default)]
+pub struct FilterResponse {
+    pub message: Cow<'static, str>,
+    pub disconnect: bool,
+}
+
+pub trait AuthResult {
+    fn as_str(&self) -> &'static str;
+}
+
+impl AuthResult for SpfResult {
+    fn as_str(&self) -> &'static str {
+        match self {
+            SpfResult::Pass => "pass",
+            SpfResult::Fail => "fail",
+            SpfResult::SoftFail => "softfail",
+            SpfResult::Neutral => "neutral",
+            SpfResult::None => "none",
+            SpfResult::TempError => "temperror",
+            SpfResult::PermError => "permerror",
+        }
+    }
+}
+
+impl AuthResult for IprevResult {
+    fn as_str(&self) -> &'static str {
+        match self {
+            IprevResult::Pass => "pass",
+            IprevResult::Fail(_) => "fail",
+            IprevResult::TempError(_) => "temperror",
+            IprevResult::PermError(_) => "permerror",
+            IprevResult::None => "none",
+        }
+    }
+}
+
+impl AuthResult for DkimResult {
+    fn as_str(&self) -> &'static str {
+        match self {
+            DkimResult::Pass => "pass",
+            DkimResult::None => "none",
+            DkimResult::Neutral(_) => "neutral",
+            DkimResult::Fail(_) => "fail",
+            DkimResult::PermError(_) => "permerror",
+            DkimResult::TempError(_) => "temperror",
+        }
+    }
+}
+
+impl AuthResult for DmarcResult {
+    fn as_str(&self) -> &'static str {
+        match self {
+            DmarcResult::Pass => "pass",
+            DmarcResult::Fail(_) => "fail",
+            DmarcResult::TempError(_) => "temperror",
+            DmarcResult::PermError(_) => "permerror",
+            DmarcResult::None => "none",
+        }
+    }
+}
+
+impl AuthResult for Policy {
+    fn as_str(&self) -> &'static str {
+        match self {
+            Policy::Reject => "reject",
+            Policy::Quarantine => "quarantine",
+            Policy::None | Policy::Unspecified => "none",
+        }
+    }
+}
+
+impl FilterResponse {
+    pub fn accept() -> Self {
+        Self {
+            message: Cow::Borrowed("250 2.0.0 Message queued for delivery.\r\n"),
+            disconnect: false,
+        }
+    }
+
+    pub fn reject() -> Self {
+        Self {
+            message: Cow::Borrowed("503 5.5.3 Message rejected.\r\n"),
+            disconnect: false,
+        }
+    }
+
+    pub fn temp_fail() -> Self {
+        Self {
+            message: Cow::Borrowed("451 4.3.5 Unable to accept message at this time.\r\n"),
+            disconnect: false,
+        }
+    }
+
+    pub fn shutdown() -> Self {
+        Self {
+            message: Cow::Borrowed("421 4.3.0 Server shutting down.\r\n"),
+            disconnect: true,
+        }
+    }
+
+    pub fn server_failure() -> Self {
+        Self {
+            message: Cow::Borrowed("451 4.3.5 Unable to accept message at this time.\r\n"),
+            disconnect: false,
+        }
+    }
+
+    pub fn disconnect(self) -> Self {
+        Self {
+            disconnect: true,
+            ..self
+        }
+    }
+
+    pub fn into_bytes(self) -> Cow<'static, [u8]> {
+        match self.message {
+            Cow::Borrowed(s) => Cow::Borrowed(s.as_bytes()),
+            Cow::Owned(s) => Cow::Owned(s.into_bytes()),
+        }
+    }
+}

crates/smtp/src/inbound/rcpt.rs

@@ -0,0 +1,458 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use crate::{
+    core::{Session, SessionAddress},
+    scripts::ScriptResult,
+};
+use common::{
+    KV_GREYLIST,
+    config::smtp::session::Stage,
+    network::{RcptResolution, SessionStream},
+    scripts::ScriptModification,
+};
+use smtp_proto::{
+    RCPT_NOTIFY_DELAY, RCPT_NOTIFY_FAILURE, RCPT_NOTIFY_NEVER, RCPT_NOTIFY_SUCCESS, RcptTo,
+};
+use std::borrow::Cow;
+use store::dispatch::lookup::KeyValue;
+use trc::{SecurityEvent, SmtpEvent};
+use utils::DomainPart;
+
+impl<T: SessionStream> Session<T> {
+    pub async fn handle_rcpt_to(&mut self, to: RcptTo<Cow<'_, str>>) -> Result<(), ()> {
+        #[cfg(feature = "test_mode")]
+        if self.instance.id.ends_with("-debug") {
+            if to.address.contains("fail@") {
+                return self.write(b"503 5.5.1 Invalid recipient.\r\n").await;
+            } else if (to.address.contains("delay-random@") && rand::random())
+                || to.address.contains("delay@")
+            {
+                return self.write(b"451 4.5.3 Try again later.\r\n").await;
+            } else if to.address.contains("slow@") {
+                tokio::time::sleep(std::time::Duration::from_secs(
+                    rand::random::<u64>() % 5 + 5,
+                ))
+                .await;
+            }
+        }
+
+        if self.data.mail_from.is_none() {
+            trc::event!(
+                Smtp(SmtpEvent::MailFromMissing),
+                SpanId = self.data.session_id,
+            );
+            return self.write(b"503 5.5.1 MAIL is required first.\r\n").await;
+        } else if std::cmp::min(self.data.rcpt_to.len(), self.data.rcpt_oks) >= self.params.rcpt_max
+        {
+            trc::event!(
+                Smtp(SmtpEvent::TooManyRecipients),
+                SpanId = self.data.session_id,
+                Limit = self.params.rcpt_max,
+            );
+            return self.write(b"455 4.5.3 Too many recipients.\r\n").await;
+        }
+
+        // Verify parameters
+        if ((to.flags
+            & (RCPT_NOTIFY_DELAY | RCPT_NOTIFY_NEVER | RCPT_NOTIFY_SUCCESS | RCPT_NOTIFY_FAILURE)
+            != 0)
+            || to.orcpt.is_some())
+            && !self.params.rcpt_dsn
+        {
+            trc::event!(Smtp(SmtpEvent::DsnDisabled), SpanId = self.data.session_id,);
+            return self
+                .write(b"501 5.5.4 DSN extension has been disabled.\r\n")
+                .await;
+        }
+
+        // Build RCPT
+        let address_lcase = to.address.to_lowercase_address(true);
+        let rcpt = SessionAddress {
+            domain: address_lcase.domain_part().into(),
+            address_lcase,
+            address: to.address.into_owned(),
+            flags: to.flags,
+            dsn_info: to.orcpt.map(|e| e.into_owned()),
+        };
+
+        if self.data.rcpt_to.contains(&rcpt) {
+            trc::event!(
+                Smtp(SmtpEvent::RcptToDuplicate),
+                SpanId = self.data.session_id,
+                To = rcpt.address_lcase,
+            );
+            self.data.rcpt_oks += 1;
+            return self.write(b"250 2.1.5 OK\r\n").await;
+        }
+        self.data.rcpt_to.push(rcpt);
+
+        // Address rewriting and Sieve filtering
+        let rcpt_config = &self.server.core.smtp.session.rcpt;
+        let rcpt_script = self
+            .server
+            .eval_if::<String, _>(&rcpt_config.script, self, self.data.session_id)
+            .await
+            .and_then(|name| {
+                self.server
+                    .get_trusted_sieve_script(&name, self.data.session_id)
+                    .map(|s| (s.clone(), name))
+            });
+
+        let session_config = &self.server.core.smtp.session;
+        if rcpt_script.is_some()
+            || !rcpt_config.rewrite.is_empty()
+            || session_config
+                .milters
+                .iter()
+                .any(|m| m.run_on_stage.contains(&Stage::Rcpt))
+            || session_config
+                .hooks
+                .iter()
+                .any(|h| h.run_on_stage.contains(&Stage::Rcpt))
+        {
+            // Sieve filtering
+            if let Some((script, script_id)) = rcpt_script {
+                match self
+                    .run_script(
+                        script_id,
+                        script.clone(),
+                        self.build_script_parameters("rcpt"),
+                    )
+                    .await
+                {
+                    ScriptResult::Accept { modifications } if !modifications.is_empty() => {
+                        for modification in modifications {
+                            if let ScriptModification::SetEnvelope { name, value } = modification {
+                                self.data.apply_envelope_modification(name, value);
+                            }
+                        }
+                    }
+                    ScriptResult::Reject(message) => {
+                        self.data.rcpt_to.pop();
+                        return self.write(message.as_bytes()).await;
+                    }
+                    _ => (),
+                }
+            }
+
+            // Milter filtering
+            if let Err(message) = self.run_milters(Stage::Rcpt, None, None).await {
+                self.data.rcpt_to.pop();
+                return self.write(message.message.as_bytes()).await;
+            }
+
+            // MTAHook filtering
+            if let Err(message) = self.run_mta_hooks(Stage::Rcpt, None, None).await {
+                self.data.rcpt_to.pop();
+                return self.write(message.message.as_bytes()).await;
+            }
+
+            // Address rewriting
+            if let Some(new_address) = self
+                .server
+                .eval_if::<String, _>(&rcpt_config.rewrite, self, self.data.session_id)
+                .await
+            {
+                let rcpt = self.data.rcpt_to.last_mut().unwrap();
+
+                trc::event!(
+                    Smtp(SmtpEvent::RcptToRewritten),
+                    SpanId = self.data.session_id,
+                    Details = rcpt.address_lcase.clone(),
+                    To = new_address.clone(),
+                );
+
+                if new_address.contains('@') {
+                    rcpt.address_lcase = new_address.to_lowercase_address(true);
+                    rcpt.domain = rcpt.address_lcase.domain_part().into();
+                    rcpt.address = new_address;
+                }
+            }
+
+            // Check for duplicates
+            let rcpt = self.data.rcpt_to.last().unwrap();
+            if self.data.rcpt_to.iter().filter(|r| r == &rcpt).count() > 1 {
+                trc::event!(
+                    Smtp(SmtpEvent::RcptToDuplicate),
+                    SpanId = self.data.session_id,
+                    To = rcpt.address_lcase.clone(),
+                );
+                self.data.rcpt_to.pop();
+                self.data.rcpt_oks += 1;
+                return self.write(b"250 2.1.5 OK\r\n").await;
+            }
+        }
+
+        // Verify address
+        let rcpt = self.data.rcpt_to.last().unwrap();
+        let mut rcpt_members = None;
+
+        match self
+            .server
+            .rcpt_resolve(&rcpt.address_lcase, true, self.data.session_id)
+            .await
+        {
+            Ok(RcptResolution::Accept) => {}
+            Ok(RcptResolution::Rewrite(address)) => {
+                let orig_addr = self.data.rcpt_to.pop().unwrap();
+                let mut new_addr = SessionAddress::new(address);
+
+                if !self.data.rcpt_to.contains(&new_addr) {
+                    new_addr.dsn_info = format!("rfc822;{}", orig_addr.address_lcase).into();
+                    new_addr.flags = orig_addr.flags;
+                    self.data.rcpt_to.push(new_addr);
+                } else {
+                    trc::event!(
+                        Smtp(SmtpEvent::RcptToDuplicate),
+                        SpanId = self.data.session_id,
+                        To = new_addr.address_lcase.clone(),
+                    );
+                    self.data.rcpt_oks += 1;
+                    return self.write(b"250 2.1.5 OK\r\n").await;
+                }
+            }
+            Ok(RcptResolution::Expand(members)) => {
+                rcpt_members = Some(members);
+            }
+            Ok(RcptResolution::UnknownRecipient) => {
+                trc::event!(
+                    Smtp(SmtpEvent::MailboxDoesNotExist),
+                    SpanId = self.data.session_id,
+                    To = rcpt.address_lcase.clone(),
+                );
+
+                let rcpt_to = self.data.rcpt_to.pop().unwrap().address_lcase;
+                return self
+                    .rcpt_error(b"550 5.1.2 Mailbox does not exist.\r\n", rcpt_to)
+                    .await;
+            }
+            Ok(RcptResolution::UnknownDomain) => {
+                if !self
+                    .server
+                    .eval_if(&rcpt_config.relay, self, self.data.session_id)
+                    .await
+                    .unwrap_or(false)
+                {
+                    trc::event!(
+                        Smtp(SmtpEvent::RelayNotAllowed),
+                        SpanId = self.data.session_id,
+                        To = rcpt.address_lcase.clone(),
+                    );
+
+                    let rcpt_to = self.data.rcpt_to.pop().unwrap().address_lcase;
+                    return self
+                        .rcpt_error(b"550 5.1.2 Relay not allowed.\r\n", rcpt_to)
+                        .await;
+                }
+            }
+            Err(err) => {
+                trc::error!(
+                    err.span_id(self.data.session_id)
+                        .caused_by(trc::location!())
+                        .details("Failed to verify address.")
+                );
+
+                self.data.rcpt_to.pop();
+                return self
+                    .write(b"451 4.4.3 Unable to verify address at this time.\r\n")
+                    .await;
+            }
+        }
+
+        if self.is_allowed().await {
+            // Greylist
+            if let Some(greylist_duration) = self
+                .server
+                .core
+                .spam
+                .grey_list_expiry
+                .filter(|_| self.data.authenticated_as.is_none())
+            {
+                let from_addr = self
+                    .data
+                    .mail_from
+                    .as_ref()
+                    .unwrap()
+                    .address_lcase
+                    .as_bytes();
+                let to_addr = self.data.rcpt_to.last().unwrap().address_lcase.as_bytes();
+                let mut key = Vec::with_capacity(from_addr.len() + to_addr.len() + 1);
+                key.push(KV_GREYLIST);
+                key.extend_from_slice(from_addr);
+                key.extend_from_slice(to_addr);
+
+                match self.server.in_memory_store().key_exists(key.clone()).await {
+                    Ok(true) => (),
+                    Ok(false) => {
+                        match self
+                            .server
+                            .in_memory_store()
+                            .key_set(KeyValue::new(key, vec![]).expires(greylist_duration))
+                            .await
+                        {
+                            Ok(_) => {
+                                let rcpt = self.data.rcpt_to.pop().unwrap();
+
+                                trc::event!(
+                                    Smtp(SmtpEvent::RcptToGreylisted),
+                                    SpanId = self.data.session_id,
+                                    To = rcpt.address_lcase,
+                                );
+
+                                return self
+                                    .write(
+                                        concat!(
+                                            "452 4.2.2 Greylisted, please try ",
+                                            "again in a few moments.\r\n"
+                                        )
+                                        .as_bytes(),
+                                    )
+                                    .await;
+                            }
+                            Err(err) => {
+                                trc::error!(
+                                    err.span_id(self.data.session_id)
+                                        .caused_by(trc::location!())
+                                        .details("Failed to set greylist.")
+                                );
+                            }
+                        }
+                    }
+                    Err(err) => {
+                        trc::error!(
+                            err.span_id(self.data.session_id)
+                                .caused_by(trc::location!())
+                                .details("Failed to check greylist.")
+                        );
+                    }
+                }
+            }
+
+            trc::event!(
+                Smtp(SmtpEvent::RcptTo),
+                SpanId = self.data.session_id,
+                To = self.data.rcpt_to.last().unwrap().address_lcase.clone(),
+            );
+        } else {
+            trc::event!(
+                Smtp(SmtpEvent::RateLimitExceeded),
+                SpanId = self.data.session_id,
+                To = self.data.rcpt_to.last().unwrap().address_lcase.clone(),
+            );
+
+            self.data.rcpt_to.pop();
+            return self
+                .write(b"452 4.4.5 Rate limit exceeded, try again later.\r\n")
+                .await;
+        }
+
+        // Expand list
+        if let Some(members) = rcpt_members {
+            let list_addr = self.data.rcpt_to.pop().unwrap();
+            let orcpt = format!("rfc822;{}", list_addr.address_lcase);
+            for member in members.as_ref() {
+                let member_lcase = member.to_lowercase();
+                let is_local = match self
+                    .server
+                    .account_id_from_email(&member_lcase, false)
+                    .await
+                {
+                    Ok(account_id) => account_id.is_some(),
+                    Err(err) => {
+                        trc::error!(
+                            err.span_id(self.data.session_id)
+                                .caused_by(trc::location!())
+                                .details("Failed to look up mailing list member.")
+                                .ctx(trc::Key::To, member.to_string())
+                        );
+                        false
+                    }
+                };
+
+                let address = if is_local {
+                    member.to_string()
+                } else {
+                    match self
+                        .server
+                        .rcpt_resolve(&member_lcase, false, self.data.session_id)
+                        .await
+                    {
+                        Ok(RcptResolution::Rewrite(address)) => address,
+                        Ok(_) => member.to_string(),
+                        Err(err) => {
+                            trc::error!(
+                                err.span_id(self.data.session_id)
+                                    .caused_by(trc::location!())
+                                    .details("Failed to resolve mailing list member.")
+                                    .ctx(trc::Key::To, member.to_string())
+                            );
+                            member.to_string()
+                        }
+                    }
+                };
+
+                let mut member_addr = SessionAddress::new(address);
+                if !self.data.rcpt_to.contains(&member_addr)
+                    && member_addr.address_lcase != list_addr.address_lcase
+                {
+                    member_addr.dsn_info = orcpt.clone().into();
+                    member_addr.flags = list_addr.flags;
+                    self.data.rcpt_to.push(member_addr);
+                }
+            }
+        }
+
+        self.data.rcpt_oks += 1;
+        self.write(b"250 2.1.5 OK\r\n").await
+    }
+
+    async fn rcpt_error(&mut self, response: &[u8], rcpt: String) -> Result<(), ()> {
+        tokio::time::sleep(self.params.rcpt_errors_wait).await;
+        self.data.rcpt_errors += 1;
+        let has_too_many_errors = self.data.rcpt_errors >= self.params.rcpt_errors_max;
+
+        match self
+            .server
+            .is_rcpt_fail2banned(self.data.remote_ip, &rcpt)
+            .await
+        {
+            Ok(true) => {
+                trc::event!(
+                    Security(SecurityEvent::AbuseBan),
+                    SpanId = self.data.session_id,
+                    RemoteIp = self.data.remote_ip,
+                    To = rcpt,
+                );
+            }
+            Ok(false) => {
+                if has_too_many_errors {
+                    trc::event!(
+                        Smtp(SmtpEvent::TooManyInvalidRcpt),
+                        SpanId = self.data.session_id,
+                        Limit = self.params.rcpt_errors_max,
+                        To = rcpt,
+                    );
+                }
+            }
+            Err(err) => {
+                trc::error!(
+                    err.span_id(self.data.session_id)
+                        .caused_by(trc::location!())
+                        .details("Failed to check if IP should be banned.")
+                );
+            }
+        }
+
+        if !has_too_many_errors {
+            self.write(response).await
+        } else {
+            self.write(b"451 4.3.0 Too many errors, disconnecting.\r\n")
+                .await?;
+            Err(())
+        }
+    }
+}

crates/smtp/src/inbound/session.rs

@@ -0,0 +1,639 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use common::{
+    config::{server::ServerProtocol, smtp::session::Mechanism},
+    expr::{self, functions::ResolveVariable, *},
+    network::SessionStream,
+};
+
+use compact_str::ToCompactString;
+use registry::schema::enums::ExpressionVariable;
+use smtp_proto::{
+    request::receiver::{
+        BdatReceiver, DataReceiver, DummyDataReceiver, DummyLineReceiver, LineReceiver,
+        MAX_LINE_LENGTH,
+    },
+    *,
+};
+use tokio::io::{AsyncRead, AsyncReadExt, AsyncWrite, AsyncWriteExt};
+use trc::{NetworkEvent, SecurityEvent, SmtpEvent};
+
+use crate::core::{Session, State};
+
+use super::auth::SaslToken;
+
+impl<T: SessionStream> Session<T> {
+    pub async fn ingest(&mut self, bytes: &[u8]) -> Result<bool, ()> {
+        let mut iter = bytes.iter();
+        let mut state = std::mem::replace(&mut self.state, State::None);
+
+        'outer: loop {
+            match &mut state {
+                State::Request(receiver) => loop {
+                    match receiver.ingest(&mut iter) {
+                        Ok(request) => match request {
+                            Request::Rcpt { to } => {
+                                self.handle_rcpt_to(to).await?;
+                            }
+                            Request::Mail { from } => {
+                                self.handle_mail_from(from).await?;
+                            }
+                            Request::Ehlo { host } => {
+                                if self.instance.protocol == ServerProtocol::Smtp {
+                                    self.handle_ehlo(host, true).await?;
+                                } else {
+                                    trc::event!(
+                                        Smtp(SmtpEvent::LhloExpected),
+                                        SpanId = self.data.session_id,
+                                    );
+
+                                    self.write(b"500 5.5.1 Invalid command.\r\n").await?;
+                                }
+                            }
+                            Request::Data => {
+                                if let Some(response) = self.can_send_data().await {
+                                    self.write(response).await?;
+                                } else {
+                                    self.write(b"354 Start mail input; end with <CRLF>.<CRLF>\r\n")
+                                        .await?;
+                                    self.data.message = Vec::with_capacity(1024);
+                                    state = State::Data(DataReceiver::new());
+                                    continue 'outer;
+                                }
+                            }
+                            Request::Bdat {
+                                chunk_size,
+                                is_last,
+                            } => {
+                                state = if let Some(response) = self.can_send_data().await {
+                                    State::SkipData(
+                                        DummyDataReceiver::new_bdat(chunk_size),
+                                        response,
+                                    )
+                                } else if chunk_size.saturating_add(self.data.message.len())
+                                    < self.params.max_message_size
+                                {
+                                    if self.data.message.is_empty() {
+                                        self.data.message = Vec::with_capacity(chunk_size);
+                                    } else {
+                                        self.data.message.reserve(chunk_size);
+                                    }
+                                    State::Bdat(BdatReceiver::new(chunk_size, is_last))
+                                } else {
+                                    trc::event!(
+                                        Smtp(SmtpEvent::MessageTooLarge),
+                                        SpanId = self.data.session_id,
+                                        Size = chunk_size.saturating_add(self.data.message.len()),
+                                        Limit = self.params.max_message_size,
+                                    );
+
+                                    State::SkipData(
+                                        DummyDataReceiver::new_bdat(chunk_size),
+                                        b"552 5.3.4 Message too big for system.\r\n",
+                                    )
+                                };
+                                continue 'outer;
+                            }
+                            Request::Auth {
+                                mechanism,
+                                initial_response,
+                            } => {
+                                let auth: u64 = self
+                                    .server
+                                    .eval_if::<Mechanism, _>(
+                                        &self.server.core.smtp.session.auth.mechanisms,
+                                        self,
+                                        self.data.session_id,
+                                    )
+                                    .await
+                                    .unwrap_or_default()
+                                    .into();
+                                if auth == 0 {
+                                    trc::event!(
+                                        Smtp(SmtpEvent::AuthNotAllowed),
+                                        SpanId = self.data.session_id,
+                                    );
+
+                                    self.write(b"503 5.5.1 AUTH not allowed.\r\n").await?;
+                                } else if let Some(authenticated_as) = self.authenticated_as() {
+                                    trc::event!(
+                                        Smtp(SmtpEvent::AlreadyAuthenticated),
+                                        SpanId = self.data.session_id,
+                                        AccountName = authenticated_as.to_string(),
+                                    );
+
+                                    self.write(b"503 5.5.1 Already authenticated.\r\n").await?;
+                                } else if let Some(mut token) =
+                                    SaslToken::from_mechanism(mechanism & auth)
+                                {
+                                    if self
+                                        .handle_sasl_response(
+                                            &mut token,
+                                            initial_response.as_bytes(),
+                                        )
+                                        .await?
+                                    {
+                                        state = State::Sasl(LineReceiver::new(token));
+                                        continue 'outer;
+                                    }
+                                } else {
+                                    trc::event!(
+                                        Smtp(SmtpEvent::AuthMechanismNotSupported),
+                                        SpanId = self.data.session_id,
+                                    );
+
+                                    self.write(
+                                        b"554 5.7.8 Authentication mechanism not supported.\r\n",
+                                    )
+                                    .await?;
+                                }
+                            }
+                            Request::Noop { .. } => {
+                                trc::event!(Smtp(SmtpEvent::Noop), SpanId = self.data.session_id,);
+
+                                self.write(b"250 2.0.0 OK\r\n").await?;
+                            }
+                            Request::Vrfy { value } => {
+                                self.handle_vrfy(value).await?;
+                            }
+                            Request::Expn { value } => {
+                                self.handle_expn(value).await?;
+                            }
+                            Request::StartTls => {
+                                if !self.stream.is_tls() {
+                                    if self.instance.acceptor.is_tls() {
+                                        trc::event!(
+                                            Smtp(SmtpEvent::StartTls),
+                                            SpanId = self.data.session_id,
+                                        );
+
+                                        self.write(b"220 2.0.0 Ready to start TLS.\r\n").await?;
+                                        #[cfg(any(test, feature = "test_mode"))]
+                                        if self.data.helo_domain.contains("badtls") {
+                                            return Err(());
+                                        }
+                                        self.state = State::default();
+                                        self.reset_tls();
+                                        return Ok(false);
+                                    } else {
+                                        trc::event!(
+                                            Smtp(SmtpEvent::StartTlsUnavailable),
+                                            SpanId = self.data.session_id,
+                                        );
+
+                                        self.write(b"502 5.7.0 TLS not available.\r\n").await?;
+                                    }
+                                } else {
+                                    trc::event!(
+                                        Smtp(SmtpEvent::StartTlsAlready),
+                                        SpanId = self.data.session_id,
+                                    );
+
+                                    self.write(b"504 5.7.4 Already in TLS mode.\r\n").await?;
+                                }
+                            }
+                            Request::Rset => {
+                                trc::event!(Smtp(SmtpEvent::Rset), SpanId = self.data.session_id,);
+
+                                self.reset();
+                                self.write(b"250 2.0.0 OK\r\n").await?;
+                            }
+                            Request::Quit => {
+                                trc::event!(Smtp(SmtpEvent::Quit), SpanId = self.data.session_id,);
+
+                                self.write(b"221 2.0.0 Bye.\r\n").await?;
+                                return Err(());
+                            }
+                            Request::Help { .. } => {
+                                trc::event!(Smtp(SmtpEvent::Help), SpanId = self.data.session_id,);
+
+                                self.write(b"250 2.0.0 Help can be found at https://stalw.art\r\n")
+                                    .await?;
+                            }
+                            Request::Helo { host } => {
+                                if self.instance.protocol == ServerProtocol::Smtp {
+                                    self.handle_ehlo(host, false).await?;
+                                } else {
+                                    trc::event!(
+                                        Smtp(SmtpEvent::LhloExpected),
+                                        SpanId = self.data.session_id,
+                                    );
+
+                                    self.write(b"500 5.5.1 Invalid command: LHLO expected.\r\n")
+                                        .await?;
+                                }
+                            }
+                            Request::Lhlo { host } => {
+                                if self.instance.protocol == ServerProtocol::Lmtp {
+                                    self.handle_ehlo(host, true).await?;
+                                } else {
+                                    trc::event!(
+                                        Smtp(SmtpEvent::EhloExpected),
+                                        SpanId = self.data.session_id,
+                                    );
+
+                                    self.write(b"502 5.5.1 Invalid command: EHLO expected.\r\n")
+                                        .await?;
+                                }
+                            }
+                            cmd @ (Request::Etrn { .. }
+                            | Request::Atrn { .. }
+                            | Request::Burl { .. }) => {
+                                trc::event!(
+                                    Smtp(SmtpEvent::CommandNotImplemented),
+                                    SpanId = self.data.session_id,
+                                    Details = format!("{cmd:?}"),
+                                );
+
+                                self.write(b"502 5.5.1 Command not implemented.\r\n")
+                                    .await?;
+                            }
+                        },
+                        Err(err) => match err {
+                            Error::NeedsMoreData { .. } => break 'outer,
+                            Error::UnknownCommand | Error::InvalidResponse { .. } => {
+                                // Check for port scanners
+                                if !self.is_authenticated() {
+                                    match self
+                                        .server
+                                        .is_scanner_fail2banned(self.data.remote_ip)
+                                        .await
+                                    {
+                                        Ok(true) => {
+                                            trc::event!(
+                                                Security(SecurityEvent::ScanBan),
+                                                SpanId = self.data.session_id,
+                                                RemoteIp = self.data.remote_ip,
+                                                Reason = "Invalid SMTP command",
+                                            );
+
+                                            return Err(());
+                                        }
+                                        Ok(false) => {}
+                                        Err(err) => {
+                                            trc::error!(
+                                                err.span_id(self.data.session_id)
+                                                    .details("Failed to check for fail2ban")
+                                            );
+                                        }
+                                    }
+                                }
+
+                                trc::event!(
+                                    Smtp(SmtpEvent::InvalidCommand),
+                                    SpanId = self.data.session_id,
+                                );
+
+                                self.write(b"500 5.5.1 Invalid command.\r\n").await?;
+                            }
+                            Error::InvalidSenderAddress => {
+                                trc::event!(
+                                    Smtp(SmtpEvent::InvalidSenderAddress),
+                                    SpanId = self.data.session_id,
+                                );
+
+                                self.write(b"501 5.1.8 Bad sender's system address.\r\n")
+                                    .await?;
+                            }
+                            Error::InvalidRecipientAddress => {
+                                trc::event!(
+                                    Smtp(SmtpEvent::InvalidRecipientAddress),
+                                    SpanId = self.data.session_id,
+                                );
+
+                                self.write(
+                                    b"501 5.1.3 Bad destination mailbox address syntax.\r\n",
+                                )
+                                .await?;
+                            }
+                            Error::SyntaxError { syntax } => {
+                                trc::event!(
+                                    Smtp(SmtpEvent::SyntaxError),
+                                    SpanId = self.data.session_id,
+                                    Details = syntax
+                                );
+
+                                if !self.params.ehlo_reject_non_fqdn && syntax.starts_with("EHLO ")
+                                {
+                                    self.handle_ehlo("null".into(), true).await?
+                                } else {
+                                    self.write(
+                                        format!("501 5.5.2 Syntax error, expected: {syntax}\r\n")
+                                            .as_bytes(),
+                                    )
+                                    .await?;
+                                }
+                            }
+                            Error::InvalidParameter { param } => {
+                                trc::event!(
+                                    Smtp(SmtpEvent::InvalidParameter),
+                                    SpanId = self.data.session_id,
+                                    Details = param
+                                );
+
+                                self.write(
+                                    format!("501 5.5.4 Invalid parameter {param:?}.\r\n")
+                                        .as_bytes(),
+                                )
+                                .await?;
+                            }
+                            Error::UnsupportedParameter { param } => {
+                                trc::event!(
+                                    Smtp(SmtpEvent::UnsupportedParameter),
+                                    SpanId = self.data.session_id,
+                                    Details = param.clone()
+                                );
+
+                                self.write(
+                                    format!("504 5.5.4 Unsupported parameter {param:?}.\r\n")
+                                        .as_bytes(),
+                                )
+                                .await?;
+                            }
+                            Error::ResponseTooLong => {
+                                state = State::RequestTooLarge(DummyLineReceiver::default());
+                                continue 'outer;
+                            }
+                        },
+                    }
+                },
+                State::Data(receiver) => {
+                    if self.data.message.len() + bytes.len() < self.params.max_message_size {
+                        if receiver.ingest(&mut iter, &mut self.data.message) {
+                            let message = self.queue_message().await;
+                            let num_responses = if self.instance.protocol == ServerProtocol::Smtp {
+                                1
+                            } else {
+                                self.data.rcpt_oks
+                            };
+                            if !message.is_empty() {
+                                for _ in 0..num_responses {
+                                    self.write(message.as_ref()).await?;
+                                }
+                                self.reset();
+                                state = State::default();
+                            } else {
+                                // Disconnect requested
+                                return Err(());
+                            }
+                        } else {
+                            break 'outer;
+                        }
+                    } else {
+                        trc::event!(
+                            Smtp(SmtpEvent::MessageTooLarge),
+                            SpanId = self.data.session_id,
+                            Size = self.data.message.len() + bytes.len(),
+                            Limit = self.params.max_message_size,
+                        );
+
+                        state = State::SkipData(
+                            DummyDataReceiver::new_data(receiver),
+                            b"552 5.3.4 Message too big for system.\r\n",
+                        );
+                    }
+                }
+                State::Bdat(receiver) => {
+                    if receiver.ingest(&mut iter, &mut self.data.message) {
+                        if receiver.is_last {
+                            let message = self.queue_message().await;
+                            if !message.is_empty() {
+                                let num_responses =
+                                    if self.instance.protocol == ServerProtocol::Smtp {
+                                        1
+                                    } else {
+                                        self.data.rcpt_oks
+                                    };
+                                for _ in 0..num_responses {
+                                    self.write(message.as_ref()).await?;
+                                }
+                                self.reset();
+                            } else {
+                                // Disconnect requested
+                                return Err(());
+                            }
+                        } else {
+                            self.write(b"250 2.6.0 Chunk accepted.\r\n").await?;
+                        }
+                        state = State::default();
+                    } else {
+                        break 'outer;
+                    }
+                }
+                State::Sasl(receiver) => {
+                    if receiver.ingest(&mut iter) {
+                        if receiver.buf.len() < MAX_LINE_LENGTH {
+                            if self
+                                .handle_sasl_response(&mut receiver.state, &receiver.buf)
+                                .await?
+                            {
+                                receiver.buf.clear();
+                                continue 'outer;
+                            }
+                        } else {
+                            trc::event!(
+                                Smtp(SmtpEvent::AuthExchangeTooLong),
+                                SpanId = self.data.session_id,
+                                Limit = MAX_LINE_LENGTH,
+                            );
+
+                            self.auth_error(
+                                b"500 5.5.6 Authentication Exchange line is too long.\r\n",
+                            )
+                            .await?;
+                        }
+                        state = State::default();
+                    } else {
+                        break 'outer;
+                    }
+                }
+                State::SkipData(receiver, response) => {
+                    if receiver.ingest(&mut iter) {
+                        self.data.message = Vec::with_capacity(0);
+                        self.write(response).await?;
+                        state = State::default();
+                    } else {
+                        break 'outer;
+                    }
+                }
+                State::RequestTooLarge(receiver) => {
+                    if receiver.ingest(&mut iter) {
+                        trc::event!(
+                            Smtp(SmtpEvent::RequestTooLarge),
+                            SpanId = self.data.session_id,
+                        );
+
+                        self.write(b"554 5.3.4 Line is too long.\r\n").await?;
+                        state = State::default();
+                    } else {
+                        break 'outer;
+                    }
+                }
+                State::None | State::Accepted(_) => unreachable!(),
+            }
+        }
+        self.state = state;
+
+        Ok(true)
+    }
+}
+
+impl<T: AsyncWrite + AsyncRead + Unpin> Session<T> {
+    pub fn reset(&mut self) {
+        self.data.mail_from = None;
+        self.data.spf_mail_from = None;
+        self.data.rcpt_to.clear();
+        self.data.message = Vec::with_capacity(0);
+        self.data.priority = 0;
+        self.data.delivery_by = 0;
+        self.data.future_release = 0;
+        self.data.rcpt_oks = 0;
+    }
+
+    pub fn reset_tls(&mut self) {
+        self.reset();
+        self.data.helo_domain.clear();
+        self.data.spf_ehlo = None;
+        self.data.authenticated_as = None;
+    }
+
+    #[inline(always)]
+    pub async fn write(&mut self, bytes: &[u8]) -> Result<(), ()> {
+        match self.stream.write_all(bytes).await {
+            Ok(_) => match self.stream.flush().await {
+                Ok(_) => {
+                    trc::event!(
+                        Smtp(SmtpEvent::RawOutput),
+                        SpanId = self.data.session_id,
+                        Size = bytes.len(),
+                        Contents = trc::Value::from_maybe_string(bytes),
+                    );
+
+                    Ok(())
+                }
+                Err(err) => {
+                    trc::event!(
+                        Network(NetworkEvent::FlushError),
+                        SpanId = self.data.session_id,
+                        Reason = err.to_string(),
+                    );
+                    Err(())
+                }
+            },
+            Err(err) => {
+                trc::event!(
+                    Network(NetworkEvent::WriteError),
+                    SpanId = self.data.session_id,
+                    Reason = err.to_string(),
+                );
+
+                Err(())
+            }
+        }
+    }
+
+    #[inline(always)]
+    pub async fn read(&mut self, bytes: &mut [u8]) -> Result<usize, ()> {
+        match self.stream.read(bytes).await {
+            Ok(len) => {
+                trc::event!(
+                    Smtp(SmtpEvent::RawInput),
+                    SpanId = self.data.session_id,
+                    Size = len,
+                    Contents =
+                        String::from_utf8_lossy(bytes.get(0..len).unwrap_or_default()).into_owned(),
+                );
+
+                Ok(len)
+            }
+            Err(err) => {
+                trc::event!(
+                    Network(NetworkEvent::ReadError),
+                    SpanId = self.data.session_id,
+                    Reason = err.to_string(),
+                );
+
+                Err(())
+            }
+        }
+    }
+}
+
+impl<T: SessionStream> ResolveVariable for Session<T> {
+    fn resolve_variable(&self, variable: ExpressionVariable) -> expr::Variable<'_> {
+        match variable {
+            ExpressionVariable::Rcpt => self
+                .data
+                .rcpt_to
+                .last()
+                .map(|r| r.address_lcase.as_str())
+                .unwrap_or_default()
+                .into(),
+            ExpressionVariable::RcptDomain => self
+                .data
+                .rcpt_to
+                .last()
+                .map(|r| r.domain.as_str())
+                .unwrap_or_default()
+                .into(),
+            ExpressionVariable::Recipients => self
+                .data
+                .rcpt_to
+                .iter()
+                .map(|r| Variable::from(r.address_lcase.as_str()))
+                .collect::<Vec<_>>()
+                .into(),
+            ExpressionVariable::Sender => self
+                .data
+                .mail_from
+                .as_ref()
+                .map(|m| m.address_lcase.as_str())
+                .unwrap_or_default()
+                .into(),
+            ExpressionVariable::SenderDomain => self
+                .data
+                .mail_from
+                .as_ref()
+                .map(|m| m.domain.as_str())
+                .unwrap_or_default()
+                .into(),
+            ExpressionVariable::HeloDomain => self.data.helo_domain.as_str().into(),
+            ExpressionVariable::AuthenticatedAs => {
+                self.authenticated_as().unwrap_or_default().into()
+            }
+            ExpressionVariable::Listener => self.instance.id.as_str().into(),
+            ExpressionVariable::RemoteIp => self.data.remote_ip_str.as_str().into(),
+            ExpressionVariable::RemotePort => self.data.remote_port.into(),
+            ExpressionVariable::LocalIp => self.data.local_ip_str.as_str().into(),
+            ExpressionVariable::LocalPort => self.data.local_port.into(),
+            ExpressionVariable::IsTls => self.stream.is_tls().into(),
+            ExpressionVariable::Priority => self.data.priority.to_compact_string().into(),
+            ExpressionVariable::Protocol => self.instance.protocol.as_str().into(),
+            ExpressionVariable::Asn => self
+                .data
+                .asn_geo_data
+                .asn
+                .as_ref()
+                .map(|a| a.id)
+                .unwrap_or_default()
+                .into(),
+            ExpressionVariable::Country => self
+                .data
+                .asn_geo_data
+                .country
+                .as_ref()
+                .map(|c| c.as_str())
+                .unwrap_or_default()
+                .into(),
+            _ => expr::Variable::default(),
+        }
+    }
+
+    fn resolve_global(&self, _: &str) -> Variable<'_> {
+        Variable::Integer(0)
+    }
+}

crates/smtp/src/inbound/spam.rs

@@ -0,0 +1,107 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use crate::core::Session;
+use common::{config::mailstore::spamfilter::SpamFilterAction, network::SessionStream};
+use mail_auth::{ArcOutput, DkimOutput, DmarcResult, dkim2::Dkim2Output, dmarc::Policy};
+use mail_parser::Message;
+use spam_filter::{
+    SpamFilterInput,
+    analysis::{
+        init::SpamFilterInit,
+        score::{SpamFilterAnalyzeScore, SpamFilterScore},
+    },
+};
+
+impl<T: SessionStream> Session<T> {
+    pub async fn spam_classify<'x>(
+        &'x self,
+        message: &'x Message<'x>,
+        dkim_result: &'x [DkimOutput<'x>],
+        dkim2_result: Option<&'x Dkim2Output<'x>>,
+        arc_result: Option<&'x ArcOutput<'x>>,
+        dmarc_result: Option<&'x DmarcResult>,
+        dmarc_policy: Option<&'x Policy>,
+    ) -> SpamFilterAction<SpamFilterScore> {
+        let server = &self.server;
+        let mut ctx = server.spam_filter_init(self.build_spam_input(
+            message,
+            dkim_result,
+            dkim2_result,
+            arc_result,
+            dmarc_result,
+            dmarc_policy,
+        ));
+
+        if !self.is_authenticated() {
+            // Spam classification
+            server.spam_filter_classify(&mut ctx).await
+        } else {
+            // Do not classify authenticated sessions
+            SpamFilterAction::Disabled
+        }
+    }
+
+    pub fn build_spam_input<'x>(
+        &'x self,
+        message: &'x Message<'x>,
+        dkim_result: &'x [DkimOutput<'x>],
+        dkim2_result: Option<&'x Dkim2Output<'x>>,
+        arc_result: Option<&'x ArcOutput>,
+        dmarc_result: Option<&'x DmarcResult>,
+        dmarc_policy: Option<&'x Policy>,
+    ) -> SpamFilterInput<'x> {
+        SpamFilterInput {
+            message,
+            span_id: self.data.session_id,
+            arc_result,
+            spf_ehlo_result: self.data.spf_ehlo.as_ref(),
+            spf_mail_from_result: self.data.spf_mail_from.as_ref(),
+            dkim_result,
+            dkim2_result,
+            dmarc_result,
+            dmarc_policy,
+            iprev_result: self.data.iprev.as_ref(),
+            remote_ip: self.data.remote_ip,
+            ehlo_domain: self.data.helo_domain.as_str().into(),
+            authenticated_as: self.data.authenticated_as.as_ref().map(|a| a.name()),
+            asn: self.data.asn_geo_data.asn.as_ref().map(|a| a.id),
+            country: self.data.asn_geo_data.country.as_ref().map(|c| c.as_str()),
+            is_tls: self.stream.is_tls(),
+            env_from: self
+                .data
+                .mail_from
+                .as_ref()
+                .map(|m| m.address_lcase.as_str())
+                .unwrap_or_default(),
+            env_from_flags: self
+                .data
+                .mail_from
+                .as_ref()
+                .map(|m| m.flags)
+                .unwrap_or_default(),
+            env_rcpt_rewritten_to: self
+                .data
+                .rcpt_to
+                .iter()
+                .map(|r| r.address_lcase.as_str())
+                .collect(),
+            env_rcpt_orig_to: self
+                .data
+                .rcpt_to
+                .iter()
+                .map(|r| {
+                    r.dsn_info
+                        .as_deref()
+                        .and_then(|info| info.strip_prefix("rfc822;"))
+                        .unwrap_or(r.address_lcase.as_str())
+                })
+                .collect(),
+            is_test: false,
+            is_train: false,
+        }
+    }
+}

crates/smtp/src/inbound/spawn.rs

@@ -0,0 +1,267 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use crate::{
+    core::{Session, SessionData, SessionParameters, SmtpSessionManager, State},
+    scripts::ScriptResult,
+};
+use common::{
+    BuildServer,
+    config::smtp::session::Stage,
+    network::{self, SessionManager, SessionStream},
+};
+use std::time::Instant;
+use tokio_rustls::server::TlsStream;
+use trc::{SecurityEvent, SmtpEvent};
+
+impl SessionManager for SmtpSessionManager {
+    async fn handle<T: SessionStream>(self, session: network::SessionData<T>) {
+        // Build server and create session
+        let server = self.inner.build_server();
+        let _in_flight = session.in_flight;
+        let mut session = Session {
+            data: SessionData::new(
+                session.local_ip,
+                session.local_port,
+                session.remote_ip,
+                session.remote_port,
+                server.lookup_asn_country(session.remote_ip).await,
+                session.session_id,
+            ),
+            hostname: "".into(),
+            server,
+            instance: session.instance,
+            state: State::default(),
+            stream: session.stream,
+            params: SessionParameters::default(),
+        };
+
+        // Enforce throttle
+        if session.is_allowed().await
+            && session.init_conn().await
+            && session.handle_conn().await
+            && session.instance.acceptor.is_tls()
+            && let Ok(mut session) = session.into_tls().await
+        {
+            session.handle_conn().await;
+        }
+    }
+
+    #[allow(clippy::manual_async_fn)]
+    fn shutdown(&self) -> impl std::future::Future<Output = ()> + Send {
+        async {
+            let _ = self
+                .inner
+                .ipc
+                .queue_tx
+                .send(common::ipc::QueueEvent::Stop)
+                .await;
+            let _ = self
+                .inner
+                .ipc
+                .report_tx
+                .send(common::ipc::ReportingEvent::Stop)
+                .await;
+        }
+    }
+}
+
+impl<T: SessionStream> Session<T> {
+    pub async fn init_conn(&mut self) -> bool {
+        self.eval_session_params().await;
+
+        let config = &self.server.core.smtp.session.connect;
+
+        // Sieve filtering
+        if let Some((script, script_id)) = self
+            .server
+            .eval_if::<String, _>(&config.script, self, self.data.session_id)
+            .await
+            .and_then(|name| {
+                self.server
+                    .get_trusted_sieve_script(&name, self.data.session_id)
+                    .map(|s| (s, name))
+            })
+            && let ScriptResult::Reject(message) = self
+                .run_script(
+                    script_id,
+                    script.clone(),
+                    self.build_script_parameters("connect"),
+                )
+                .await
+        {
+            let _ = self.write(message.as_bytes()).await;
+            return false;
+        }
+
+        // Milter filtering
+        if let Err(message) = self.run_milters(Stage::Connect, None, None).await {
+            let _ = self.write(message.message.as_bytes()).await;
+            return false;
+        }
+
+        // MTAHook filtering
+        if let Err(message) = self.run_mta_hooks(Stage::Connect, None, None).await {
+            let _ = self.write(message.message.as_bytes()).await;
+            return false;
+        }
+
+        // Obtain hostname
+        self.hostname = self
+            .server
+            .eval_if::<String, _>(&config.hostname, self, self.data.session_id)
+            .await
+            .unwrap_or_default();
+        if self.hostname.is_empty() {
+            trc::event!(
+                Smtp(SmtpEvent::MissingLocalHostname),
+                SpanId = self.data.session_id,
+            );
+            self.hostname = "localhost".into();
+        }
+
+        // Obtain greeting
+        let greeting = self
+            .server
+            .eval_if::<String, _>(&config.greeting, self, self.data.session_id)
+            .await
+            .filter(|g| !g.is_empty())
+            .map(|g| format!("220 {}\r\n", g))
+            .unwrap_or_else(|| "220 Stalwart ESMTP at your service.\r\n".to_string());
+
+        if self.write(greeting.as_bytes()).await.is_err() {
+            return false;
+        }
+
+        true
+    }
+
+    pub async fn handle_conn(&mut self) -> bool {
+        let mut buf = vec![0; 8192];
+        let mut shutdown_rx = self.instance.shutdown_rx.clone();
+
+        loop {
+            tokio::select! {
+                result = tokio::time::timeout(
+                    self.params.timeout,
+                    self.read(&mut buf)) => {
+                        match result {
+                            Ok(Ok(bytes_read)) => {
+                                if bytes_read > 0 {
+                                    if Instant::now() < self.data.valid_until && bytes_read <= self.data.bytes_left  {
+                                        self.data.bytes_left -= bytes_read;
+                                        match Box::pin(self.ingest(&buf[..bytes_read])).await {
+                                            Ok(true) => (),
+                                            Ok(false) => {
+                                                return true;
+                                            }
+                                            Err(_) => {
+                                                break;
+                                            }
+                                        }
+                                    } else if bytes_read > self.data.bytes_left {
+                                        self
+                                            .write(format!("452 4.7.28 {} Session exceeded transfer quota.\r\n", self.hostname).as_bytes())
+                                            .await
+                                            .ok();
+
+                                        trc::event!(
+                                            Smtp(SmtpEvent::TransferLimitExceeded),
+                                            SpanId = self.data.session_id,
+                                        );
+
+                                        break;
+                                    } else {
+                                        self
+                                            .write(format!("421 4.3.2 {} Session open for too long.\r\n", self.hostname).as_bytes())
+                                            .await
+                                            .ok();
+
+                                        match self.server.is_loiter_fail2banned(self.data.remote_ip)
+                                            .await
+                                        {
+                                            Ok(true) => {
+                                                trc::event!(
+                                                    Security(SecurityEvent::LoiterBan),
+                                                    SpanId = self.data.session_id,
+                                                    RemoteIp = self.data.remote_ip,
+                                                );
+                                            }
+                                            Ok(false) => {
+                                                trc::event!(
+                                                    Smtp(SmtpEvent::TimeLimitExceeded),
+                                                    SpanId = self.data.session_id,
+                                                );
+                                            }
+                                            Err(err) => {
+                                                trc::error!(err
+                                                    .span_id(self.data.session_id)
+                                                    .caused_by(trc::location!())
+                                                    .details("Failed to check if IP should be banned."));
+                                            }
+                                        }
+
+                                        break;
+                                    }
+                                } else {
+                                    trc::event!(
+                                        Network(trc::NetworkEvent::Closed),
+                                        SpanId = self.data.session_id,
+                                        CausedBy = trc::location!()
+                                    );
+
+                                    break;
+                                }
+                            }
+                            Ok(Err(_)) => {
+                                break;
+                            }
+                            Err(_) => {
+                                trc::event!(
+                                    Network(trc::NetworkEvent::Timeout),
+                                    SpanId = self.data.session_id,
+                                    CausedBy = trc::location!()
+                                );
+
+                                self
+                                    .write(format!("221 2.0.0 {} Disconnecting inactive client.\r\n", self.hostname).as_bytes())
+                                    .await
+                                    .ok();
+                                break;
+                            }
+                        }
+                },
+                _ = shutdown_rx.changed() => {
+                    trc::event!(
+                        Network(trc::NetworkEvent::Closed),
+                        SpanId = self.data.session_id,
+                        Reason = "Server shutting down",
+                        CausedBy = trc::location!()
+                    );
+                    self.write(format!("421 4.3.0 {} Server shutting down.\r\n", self.hostname).as_bytes()).await.ok();
+                    break;
+                }
+            };
+        }
+
+        false
+    }
+
+    pub async fn into_tls(self) -> Result<Session<TlsStream<T>>, ()> {
+        Ok(Session {
+            hostname: self.hostname,
+            stream: self
+                .instance
+                .tls_accept(self.stream, self.data.session_id)
+                .await?,
+            state: self.state,
+            data: self.data,
+            instance: self.instance,
+            server: self.server,
+            params: self.params,
+        })
+    }
+}

crates/smtp/src/inbound/vrfy.rs

@@ -0,0 +1,130 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use crate::core::Session;
+use common::network::{RcptResolution, SessionStream};
+use std::{borrow::Cow, fmt::Write};
+use trc::SmtpEvent;
+use utils::DomainPart;
+
+impl<T: SessionStream> Session<T> {
+    pub async fn handle_vrfy(&mut self, address: Cow<'_, str>) -> Result<(), ()> {
+        if self.params.can_vrfy {
+            match self
+                .server
+                .rcpt_resolve(
+                    &address.to_lowercase_address(true),
+                    true,
+                    self.data.session_id,
+                )
+                .await
+            {
+                Ok(RcptResolution::Accept | RcptResolution::Rewrite(_)) => {
+                    trc::event!(
+                        Smtp(SmtpEvent::Vrfy),
+                        SpanId = self.data.session_id,
+                        To = address.as_ref().to_string(),
+                    );
+
+                    self.write(format!("250 {}\r\n", address.as_ref()).as_bytes())
+                        .await
+                }
+                Ok(
+                    RcptResolution::UnknownRecipient
+                    | RcptResolution::UnknownDomain
+                    | RcptResolution::Expand(_),
+                ) => {
+                    trc::event!(
+                        Smtp(SmtpEvent::VrfyNotFound),
+                        SpanId = self.data.session_id,
+                        To = address.as_ref().to_string(),
+                    );
+
+                    self.write(b"550 5.1.2 Address not found.\r\n").await
+                }
+                Err(err) => {
+                    trc::error!(
+                        err.span_id(self.data.session_id)
+                            .caused_by(trc::location!())
+                            .details("Failed to verify address.")
+                    );
+
+                    self.write(b"252 2.4.3 Unable to verify address at this time.\r\n")
+                        .await
+                }
+            }
+        } else {
+            trc::event!(
+                Smtp(SmtpEvent::VrfyDisabled),
+                SpanId = self.data.session_id,
+                To = address.as_ref().to_string(),
+            );
+
+            self.write(b"252 2.5.1 VRFY is disabled.\r\n").await
+        }
+    }
+
+    pub async fn handle_expn(&mut self, address: Cow<'_, str>) -> Result<(), ()> {
+        if self.params.can_expn {
+            match self
+                .server
+                .rcpt_resolve(
+                    &address.to_lowercase_address(true),
+                    true,
+                    self.data.session_id,
+                )
+                .await
+            {
+                Ok(RcptResolution::Expand(addresses)) => {
+                    let mut result = String::with_capacity(32);
+                    for (pos, value) in addresses.iter().enumerate() {
+                        let _ = write!(
+                            result,
+                            "250{}{}\r\n",
+                            if pos == addresses.len() - 1 { " " } else { "-" },
+                            value
+                        );
+                    }
+
+                    trc::event!(
+                        Smtp(SmtpEvent::Expn),
+                        SpanId = self.data.session_id,
+                        To = address.as_ref().to_string(),
+                    );
+
+                    self.write(result.as_bytes()).await
+                }
+                Ok(_) => {
+                    trc::event!(
+                        Smtp(SmtpEvent::ExpnNotFound),
+                        SpanId = self.data.session_id,
+                        To = address.as_ref().to_string(),
+                    );
+
+                    self.write(b"550 5.1.2 Mailing list not found.\r\n").await
+                }
+                Err(err) => {
+                    trc::error!(
+                        err.span_id(self.data.session_id)
+                            .caused_by(trc::location!())
+                            .details("Failed to verify address.")
+                    );
+
+                    self.write(b"252 2.4.3 Unable to expand mailing list at this time.\r\n")
+                        .await
+                }
+            }
+        } else {
+            trc::event!(
+                Smtp(SmtpEvent::ExpnDisabled),
+                SpanId = self.data.session_id,
+                To = address.as_ref().to_string(),
+            );
+
+            self.write(b"252 2.5.1 EXPN is disabled.\r\n").await
+        }
+    }
+}

crates/smtp/src/lib.rs

@@ -0,0 +1,49 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+#![warn(clippy::large_futures)]
+
+use common::{
+    Inner,
+    manager::boot::{BootManager, IpcReceivers},
+};
+use queue::manager::SpawnQueue;
+use reporting::scheduler::SpawnReport;
+use std::sync::Arc;
+
+pub mod core;
+pub mod inbound;
+pub mod outbound;
+pub mod queue;
+pub mod reporting;
+pub mod scripts;
+
+pub trait StartQueueManager {
+    fn start_queue_manager(&mut self);
+}
+
+pub trait SpawnQueueManager {
+    fn spawn_queue_manager(&mut self, inner: Arc<Inner>);
+}
+
+impl StartQueueManager for BootManager {
+    fn start_queue_manager(&mut self) {
+        self.ipc_rxs.spawn_queue_manager(self.inner.clone());
+    }
+}
+
+impl SpawnQueueManager for IpcReceivers {
+    fn spawn_queue_manager(&mut self, inner: Arc<Inner>) {
+        let core = inner.shared_core.load();
+        if !core.storage.registry.is_recovery_mode() && core.network.roles.outbound_mta {
+            // Spawn queue manager
+            self.queue_rx.take().unwrap().spawn(inner.clone());
+
+            // Spawn report manager
+            self.report_rx.take().unwrap().spawn(inner);
+        }
+    }
+}

crates/smtp/src/outbound/client.rs

@@ -0,0 +1,773 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use super::session::SessionParams;
+use crate::{
+    outbound::error::{AssertReply, ClientError, ClientResult},
+    queue::{Error, ErrorDetails, HostResponse, MessageWrapper, Status},
+};
+use base64::{Engine, engine::general_purpose};
+use directory::Credentials;
+use rustls::ClientConnection;
+use rustls_pki_types::ServerName;
+use smtp_proto::{
+    AUTH_LOGIN, AUTH_OAUTHBEARER, AUTH_PLAIN, AUTH_XOAUTH2, EXT_START_TLS, EhloResponse, Response,
+    response::{
+        generate::BitToString,
+        parser::{MAX_RESPONSE_LENGTH, ResponseReceiver},
+    },
+};
+use std::{
+    net::{IpAddr, SocketAddr},
+    time::Duration,
+};
+use tokio::{
+    io::{AsyncRead, AsyncReadExt, AsyncWrite, AsyncWriteExt},
+    net::{TcpSocket, TcpStream},
+};
+use tokio_rustls::{TlsConnector, client::TlsStream};
+use trc::DeliveryEvent;
+
+pub struct SmtpClient<T: AsyncRead + AsyncWrite> {
+    pub stream: T,
+    pub timeout: Duration,
+    pub session_id: u64,
+}
+
+impl<T: AsyncRead + AsyncWrite + Unpin> SmtpClient<T> {
+    pub async fn authenticate(
+        &mut self,
+        credentials: &Credentials,
+        capabilities: impl AsRef<EhloResponse<String>>,
+    ) -> ClientResult<&mut Self> {
+        let capabilities = capabilities.as_ref();
+        let mut available_mechanisms = match &credentials {
+            Credentials::Basic { .. } => AUTH_LOGIN | AUTH_PLAIN,
+            Credentials::Bearer { .. } => AUTH_OAUTHBEARER | AUTH_XOAUTH2,
+        } & capabilities.auth_mechanisms;
+
+        // Try authenticating from most secure to least secure
+        let mut has_err = None;
+        let mut has_failed = false;
+
+        while available_mechanisms != 0 && !has_failed {
+            let mechanism = 1 << ((63 - available_mechanisms.leading_zeros()) as u64);
+            available_mechanisms ^= mechanism;
+            match self.auth(mechanism, credentials).await {
+                Ok(_) => {
+                    return Ok(self);
+                }
+                Err(err) => match err {
+                    ClientError::UnexpectedReply(reply) => {
+                        has_failed = reply.code() == 535;
+                        has_err = reply.into();
+                    }
+                    ClientError::UnsupportedAuthMechanism => (),
+                    _ => return Err(err),
+                },
+            }
+        }
+
+        if let Some(has_err) = has_err {
+            Err(ClientError::AuthenticationFailed(has_err))
+        } else {
+            Err(ClientError::UnsupportedAuthMechanism)
+        }
+    }
+
+    pub(crate) async fn auth(
+        &mut self,
+        mechanism: u64,
+        credentials: &Credentials,
+    ) -> ClientResult<()> {
+        let mut reply = if (mechanism & (AUTH_PLAIN | AUTH_XOAUTH2 | AUTH_OAUTHBEARER)) != 0 {
+            self.cmd(
+                format!(
+                    "AUTH {} {}\r\n",
+                    mechanism.to_mechanism(),
+                    encode_credentials(credentials, mechanism, "")?,
+                )
+                .as_bytes(),
+            )
+            .await?
+        } else {
+            self.cmd(format!("AUTH {}\r\n", mechanism.to_mechanism()).as_bytes())
+                .await?
+        };
+
+        for _ in 0..3 {
+            match reply.code() {
+                334 => {
+                    reply = self
+                        .cmd(
+                            format!(
+                                "{}\r\n",
+                                encode_credentials(credentials, mechanism, reply.message())?
+                            )
+                            .as_bytes(),
+                        )
+                        .await?;
+                }
+                235 => {
+                    return Ok(());
+                }
+                _ => {
+                    return Err(ClientError::UnexpectedReply(Box::new(reply)));
+                }
+            }
+        }
+
+        Err(ClientError::UnexpectedReply(Box::new(reply)))
+    }
+
+    pub async fn read_greeting(
+        &mut self,
+        hostname: &str,
+    ) -> Result<(), Status<HostResponse<Box<str>>, ErrorDetails>> {
+        tokio::time::timeout(self.timeout, self.read())
+            .await
+            .map_err(|_| Status::timeout(hostname, "reading greeting"))?
+            .and_then(|r| r.assert_code(220))
+            .map_err(|err| Status::from_smtp_error(hostname, "", err))
+    }
+
+    pub async fn read_smtp_data_response(
+        &mut self,
+        hostname: &str,
+        bdat_cmd: &Option<String>,
+    ) -> Result<Response<String>, Status<HostResponse<Box<str>>, ErrorDetails>> {
+        tokio::time::timeout(self.timeout, self.read())
+            .await
+            .map_err(|_| Status::timeout(hostname, "reading SMTP DATA response"))?
+            .map_err(|err| {
+                Status::from_smtp_error(hostname, bdat_cmd.as_deref().unwrap_or("DATA"), err)
+            })
+    }
+
+    pub async fn read_lmtp_data_response(
+        &mut self,
+        hostname: &str,
+        num_responses: usize,
+    ) -> Result<Vec<Response<Box<str>>>, Status<HostResponse<Box<str>>, ErrorDetails>> {
+        tokio::time::timeout(self.timeout, async { self.read_many(num_responses).await })
+            .await
+            .map_err(|_| Status::timeout(hostname, "reading LMTP DATA responses"))?
+            .map_err(|err| Status::from_smtp_error(hostname, "", err))
+    }
+
+    pub async fn write_chunks(&mut self, chunks: &[&[u8]]) -> Result<(), ClientError> {
+        for chunk in chunks {
+            self.stream
+                .write_all(chunk)
+                .await
+                .map_err(ClientError::from)?;
+        }
+        self.stream.flush().await.map_err(ClientError::from)
+    }
+
+    pub async fn send_message(
+        &mut self,
+        message: &MessageWrapper,
+        rcpt_headers: Option<&[u8]>,
+        bdat_cmd: &mut Option<String>,
+        params: &SessionParams<'_>,
+    ) -> Result<(), Status<HostResponse<Box<str>>, ErrorDetails>> {
+        match params
+            .server
+            .blob_store()
+            .get_blob(message.message.blob_hash.as_slice(), 0..usize::MAX)
+            .await
+        {
+            Ok(Some(raw_message)) => {
+                tokio::time::timeout(params.conn_strategy.timeout_data, async {
+                    if let Some(bdat_cmd) = bdat_cmd {
+                        *bdat_cmd = format!(
+                            "BDAT {} LAST\r\n",
+                            raw_message.len() + rcpt_headers.map(|h| h.len()).unwrap_or(0)
+                        );
+
+                        trc::event!(
+                            Delivery(DeliveryEvent::RawOutput),
+                            SpanId = self.session_id,
+                            Contents = bdat_cmd.clone(),
+                            Size = bdat_cmd.len()
+                        );
+
+                        let chunks = if let Some(rcpt_headers) = rcpt_headers {
+                            &[bdat_cmd.as_bytes(), rcpt_headers, &raw_message][..]
+                        } else {
+                            &[bdat_cmd.as_bytes(), &raw_message][..]
+                        };
+
+                        self.write_chunks(chunks).await
+                    } else {
+                        trc::event!(
+                            Delivery(DeliveryEvent::RawOutput),
+                            SpanId = self.session_id,
+                            Contents = "DATA\r\n",
+                            Size = 6
+                        );
+
+                        self.write_chunks(&[b"DATA\r\n"]).await?;
+                        self.read().await?.assert_code(354)?;
+                        if let Some(rcpt_headers) = rcpt_headers
+                            && let Err(err) = self.write_chunks(&[rcpt_headers]).await
+                        {
+                            Err(err)
+                        } else {
+                            self.write_message(&raw_message)
+                                .await
+                                .map_err(ClientError::from)
+                        }
+                    }
+                })
+                .await
+                .map_err(|_| Status::timeout(params.hostname, "sending message"))?
+                .map_err(|err| {
+                    Status::from_smtp_error(
+                        params.hostname,
+                        bdat_cmd.as_deref().unwrap_or("DATA"),
+                        err,
+                    )
+                })
+            }
+            Ok(None) => {
+                trc::event!(
+                    Queue(trc::QueueEvent::BlobNotFound),
+                    SpanId = message.span_id,
+                    BlobId = message.message.blob_hash.to_hex(),
+                    CausedBy = trc::location!()
+                );
+                Err(Status::TemporaryFailure(ErrorDetails {
+                    entity: "localhost".into(),
+                    details: Error::Io("Queue system error.".into()),
+                }))
+            }
+            Err(err) => {
+                trc::error!(
+                    err.span_id(message.span_id)
+                        .details("Failed to fetch blobId")
+                        .caused_by(trc::location!())
+                );
+
+                Err(Status::TemporaryFailure(ErrorDetails {
+                    entity: "localhost".into(),
+                    details: Error::Io("Queue system error.".into()),
+                }))
+            }
+        }
+    }
+
+    pub async fn say_helo(
+        &mut self,
+        params: &SessionParams<'_>,
+    ) -> Result<EhloResponse<String>, Status<HostResponse<Box<str>>, ErrorDetails>> {
+        let cmd = if params.is_smtp {
+            format!("EHLO {}\r\n", params.local_hostname)
+        } else {
+            format!("LHLO {}\r\n", params.local_hostname)
+        };
+
+        trc::event!(
+            Delivery(DeliveryEvent::RawOutput),
+            SpanId = self.session_id,
+            Contents = cmd.clone(),
+            Size = cmd.len()
+        );
+
+        tokio::time::timeout(params.conn_strategy.timeout_ehlo, async {
+            self.stream.write_all(cmd.as_bytes()).await?;
+            self.stream.flush().await?;
+            self.read_ehlo().await
+        })
+        .await
+        .map_err(|_| Status::timeout(params.hostname, "reading EHLO response"))?
+        .map_err(|err| Status::from_smtp_error(params.hostname, &cmd, err))
+    }
+
+    pub async fn quit(mut self: SmtpClient<T>) {
+        trc::event!(
+            Delivery(DeliveryEvent::RawOutput),
+            SpanId = self.session_id,
+            Contents = "QUIT\r\n",
+            Size = 6
+        );
+
+        let _ = tokio::time::timeout(Duration::from_secs(10), async {
+            if self.stream.write_all(b"QUIT\r\n").await.is_ok() && self.stream.flush().await.is_ok()
+            {
+                let mut buf = [0u8; 128];
+                let _ = self.stream.read(&mut buf).await;
+            }
+        })
+        .await;
+    }
+
+    pub async fn read_ehlo(&mut self) -> ClientResult<EhloResponse<String>> {
+        let mut buf = vec![0u8; 8192];
+        let mut buf_concat = Vec::with_capacity(0);
+
+        loop {
+            let br = self.stream.read(&mut buf).await?;
+
+            if br == 0 {
+                return Err(ClientError::UnparseableReply);
+            }
+
+            trc::event!(
+                Delivery(DeliveryEvent::RawInput),
+                SpanId = self.session_id,
+                Contents = trc::Value::from_maybe_string(&buf[..br]),
+                Size = br,
+            );
+
+            let mut iter = if buf_concat.is_empty() {
+                buf[..br].iter()
+            } else if br + buf_concat.len() < MAX_RESPONSE_LENGTH {
+                buf_concat.extend_from_slice(&buf[..br]);
+                buf_concat.iter()
+            } else {
+                return Err(ClientError::UnparseableReply);
+            };
+
+            match EhloResponse::parse(&mut iter) {
+                Ok(reply) => return Ok(reply),
+                Err(err) => match err {
+                    smtp_proto::Error::NeedsMoreData { .. } => {
+                        if buf_concat.is_empty() {
+                            buf_concat = buf[..br].to_vec();
+                        }
+                    }
+                    smtp_proto::Error::InvalidResponse { code } => {
+                        match ResponseReceiver::from_code(code).parse(&mut iter) {
+                            Ok(response) => {
+                                return Err(ClientError::UnexpectedReply(Box::new(response)));
+                            }
+                            Err(smtp_proto::Error::NeedsMoreData { .. }) => {
+                                if buf_concat.is_empty() {
+                                    buf_concat = buf[..br].to_vec();
+                                }
+                            }
+                            Err(_) => return Err(ClientError::UnparseableReply),
+                        }
+                    }
+                    _ => {
+                        return Err(ClientError::UnparseableReply);
+                    }
+                },
+            }
+        }
+    }
+
+    pub async fn read(&mut self) -> ClientResult<Response<String>> {
+        let mut buf = vec![0u8; 8192];
+        let mut parser = ResponseReceiver::default();
+
+        loop {
+            let br = self.stream.read(&mut buf).await?;
+
+            if br > 0 {
+                trc::event!(
+                    Delivery(DeliveryEvent::RawInput),
+                    SpanId = self.session_id,
+                    Contents = trc::Value::from_maybe_string(&buf[..br]),
+                    Size = br
+                );
+
+                match parser.parse(&mut buf[..br].iter()) {
+                    Ok(reply) => return Ok(reply),
+                    Err(err) => match err {
+                        smtp_proto::Error::NeedsMoreData { .. } => (),
+                        _ => {
+                            return Err(ClientError::UnparseableReply);
+                        }
+                    },
+                }
+            } else {
+                return Err(ClientError::UnparseableReply);
+            }
+        }
+    }
+
+    pub async fn read_many(&mut self, num: usize) -> ClientResult<Vec<Response<Box<str>>>> {
+        let mut buf = vec![0u8; 1024];
+        let mut response = Vec::with_capacity(num);
+        let mut parser = ResponseReceiver::default();
+
+        'outer: loop {
+            let br = self.stream.read(&mut buf).await?;
+
+            if br > 0 {
+                let mut iter = buf[..br].iter();
+
+                trc::event!(
+                    Delivery(DeliveryEvent::RawInput),
+                    SpanId = self.session_id,
+                    Contents = trc::Value::from_maybe_string(&buf[..br]),
+                    Size = br
+                );
+
+                loop {
+                    match parser.parse(&mut iter) {
+                        Ok(reply) => {
+                            response.push(reply.into_box());
+                            if response.len() != num {
+                                parser.reset();
+                            } else {
+                                break 'outer;
+                            }
+                        }
+                        Err(err) => match err {
+                            smtp_proto::Error::NeedsMoreData { .. } => break,
+                            _ => {
+                                return Err(ClientError::UnparseableReply);
+                            }
+                        },
+                    }
+                }
+            } else {
+                return Err(ClientError::UnparseableReply);
+            }
+        }
+
+        Ok(response)
+    }
+
+    /// Sends a command to the SMTP server and waits for a reply.
+    pub async fn cmd(&mut self, cmd: impl AsRef<[u8]>) -> ClientResult<Response<String>> {
+        tokio::time::timeout(self.timeout, async {
+            let cmd = cmd.as_ref();
+
+            trc::event!(
+                Delivery(DeliveryEvent::RawOutput),
+                SpanId = self.session_id,
+                Contents = trc::Value::from_maybe_string(cmd),
+                Size = cmd.len()
+            );
+
+            self.stream.write_all(cmd).await?;
+            self.stream.flush().await?;
+            self.read().await
+        })
+        .await
+        .map_err(|_| ClientError::Timeout)?
+    }
+
+    pub async fn write_message(&mut self, message: &[u8]) -> tokio::io::Result<()> {
+        // Transparency procedure
+        let mut is_cr_or_lf = false;
+
+        // As per RFC 5322bis, section 2.3:
+        // CR and LF MUST only occur together as CRLF; they MUST NOT appear
+        // independently in the body.
+        // For this reason, we apply the transparency procedure when there is
+        // a CR or LF followed by a dot.
+
+        trc::event!(
+            Delivery(DeliveryEvent::RawOutput),
+            SpanId = self.session_id,
+            Contents = "[message]",
+            Size = message.len() + 5
+        );
+
+        let mut last_pos = 0;
+        for (pos, byte) in message.iter().enumerate() {
+            if *byte == b'.' && is_cr_or_lf {
+                if let Some(bytes) = message.get(last_pos..pos) {
+                    self.stream.write_all(bytes).await?;
+                    self.stream.write_all(b".").await?;
+                    last_pos = pos;
+                }
+                is_cr_or_lf = false;
+            } else {
+                is_cr_or_lf = *byte == b'\n' || *byte == b'\r';
+            }
+        }
+        if let Some(bytes) = message.get(last_pos..) {
+            self.stream.write_all(bytes).await?;
+        }
+        self.stream.write_all("\r\n.\r\n".as_bytes()).await?;
+        self.stream.flush().await
+    }
+}
+
+impl SmtpClient<TcpStream> {
+    /// Upgrade the connection to TLS.
+    pub async fn start_tls(
+        mut self,
+        tls_connector: &TlsConnector,
+        hostname: &str,
+    ) -> ClientResult<SmtpClient<TlsStream<TcpStream>>> {
+        // Send STARTTLS command
+        self.cmd(b"STARTTLS\r\n")
+            .await?
+            .assert_positive_completion()?;
+
+        self.into_tls(tls_connector, hostname).await
+    }
+
+    pub async fn into_tls(
+        self,
+        tls_connector: &TlsConnector,
+        hostname: &str,
+    ) -> ClientResult<SmtpClient<TlsStream<TcpStream>>> {
+        tokio::time::timeout(self.timeout, async {
+            Ok(SmtpClient {
+                stream: tls_connector
+                    .connect(
+                        ServerName::try_from(hostname)
+                            .map_err(|_| ClientError::InvalidTLSName)?
+                            .to_owned(),
+                        self.stream,
+                    )
+                    .await
+                    .map_err(|err| {
+                        let kind = err.kind();
+                        if let Some(inner) = err.into_inner() {
+                            match inner.downcast::<rustls::Error>() {
+                                Ok(error) => ClientError::Tls(error),
+                                Err(error) => ClientError::Io(std::io::Error::new(kind, error)),
+                            }
+                        } else {
+                            ClientError::Io(std::io::Error::new(kind, "Unspecified"))
+                        }
+                    })?,
+                timeout: self.timeout,
+                session_id: self.session_id,
+            })
+        })
+        .await
+        .map_err(|_| ClientError::Timeout)?
+    }
+}
+
+impl SmtpClient<TcpStream> {
+    /// Connects to a remote host address
+    pub async fn connect(
+        remote_addr: SocketAddr,
+        timeout: Duration,
+        session_id: u64,
+    ) -> ClientResult<Self> {
+        tokio::time::timeout(timeout, async {
+            Ok(SmtpClient {
+                stream: TcpStream::connect(remote_addr).await?,
+                timeout,
+                session_id,
+            })
+        })
+        .await
+        .map_err(|_| ClientError::Timeout)?
+    }
+
+    /// Connects to a remote host address using the provided local IP
+    pub async fn connect_using(
+        local_ip: IpAddr,
+        remote_addr: SocketAddr,
+        timeout: Duration,
+        session_id: u64,
+    ) -> ClientResult<Self> {
+        tokio::time::timeout(timeout, async {
+            let socket = if local_ip.is_ipv4() {
+                TcpSocket::new_v4()?
+            } else {
+                TcpSocket::new_v6()?
+            };
+            socket.bind(SocketAddr::new(local_ip, 0))?;
+
+            Ok(SmtpClient {
+                stream: socket.connect(remote_addr).await?,
+                timeout,
+                session_id,
+            })
+        })
+        .await
+        .map_err(|_| ClientError::Timeout)?
+    }
+
+    pub async fn try_start_tls(
+        mut self,
+        tls_connector: &TlsConnector,
+        hostname: &str,
+        capabilities: &EhloResponse<String>,
+    ) -> StartTlsResult {
+        if capabilities.has_capability(EXT_START_TLS) {
+            match self.cmd("STARTTLS\r\n").await {
+                Ok(response) => {
+                    if response.code() == 220 {
+                        match self.into_tls(tls_connector, hostname).await {
+                            Ok(smtp_client) => StartTlsResult::Success { smtp_client },
+                            Err(error) => StartTlsResult::Error { error },
+                        }
+                    } else {
+                        StartTlsResult::Unavailable {
+                            response: response.into_box().into(),
+                            smtp_client: self,
+                        }
+                    }
+                }
+                Err(error) => StartTlsResult::Error { error },
+            }
+        } else {
+            StartTlsResult::Unavailable {
+                smtp_client: self,
+                response: None,
+            }
+        }
+    }
+}
+
+fn encode_credentials(
+    credentials: &Credentials,
+    mechanism: u64,
+    challenge: &str,
+) -> ClientResult<String> {
+    Ok(general_purpose::STANDARD.encode(
+        match (mechanism, credentials) {
+            (
+                AUTH_PLAIN,
+                Credentials::Basic {
+                    username, secret, ..
+                },
+            ) => {
+                format!("\u{0}{}\u{0}{}", username, secret)
+            }
+            (
+                AUTH_LOGIN,
+                Credentials::Basic {
+                    username, secret, ..
+                },
+            ) => {
+                let challenge = general_purpose::STANDARD.decode(challenge)?;
+
+                if b"user name"
+                    .eq_ignore_ascii_case(challenge.get(0..9).ok_or(ClientError::InvalidChallenge)?)
+                    || b"username".eq_ignore_ascii_case(
+                        // Because Google makes its own standards
+                        challenge.get(0..8).ok_or(ClientError::InvalidChallenge)?,
+                    )
+                {
+                    &username
+                } else if b"password"
+                    .eq_ignore_ascii_case(challenge.get(0..8).ok_or(ClientError::InvalidChallenge)?)
+                {
+                    &secret
+                } else {
+                    return Err(ClientError::InvalidChallenge);
+                }
+                .to_string()
+            }
+
+            (AUTH_XOAUTH2, Credentials::Bearer { token, username }) => format!(
+                "user={}\x01auth=Bearer {}\x01\x01",
+                username.as_deref().unwrap_or_default(),
+                token
+            ),
+            (AUTH_OAUTHBEARER, Credentials::Bearer { token, .. }) => token.to_string(),
+            _ => return Err(ClientError::UnsupportedAuthMechanism),
+        }
+        .as_bytes(),
+    ))
+}
+
+impl SmtpClient<TlsStream<TcpStream>> {
+    pub fn tls_connection(&self) -> &ClientConnection {
+        self.stream.get_ref().1
+    }
+}
+
+#[allow(clippy::large_enum_variant)]
+pub enum StartTlsResult {
+    Success {
+        smtp_client: SmtpClient<TlsStream<TcpStream>>,
+    },
+    Error {
+        error: ClientError,
+    },
+    Unavailable {
+        response: Option<Response<Box<str>>>,
+        smtp_client: SmtpClient<TcpStream>,
+    },
+}
+
+pub(crate) trait BoxResponse {
+    fn into_box(self) -> Response<Box<str>>;
+}
+
+impl BoxResponse for Response<String> {
+    fn into_box(self) -> Response<Box<str>> {
+        Response {
+            code: self.code,
+            esc: self.esc,
+            message: self.message.into_boxed_str(),
+        }
+    }
+}
+
+pub(crate) fn from_mail_send_error(error: &ClientError) -> trc::Error {
+    let event = trc::EventType::Smtp(trc::SmtpEvent::Error).into_err();
+    match error {
+        ClientError::Io(err) => event.details("I/O Error").reason(err),
+        ClientError::Tls(err) => event.details("TLS Error").reason(err),
+        ClientError::Base64(err) => event.details("Base64 Error").reason(err),
+        ClientError::InvalidChallenge => event
+            .details("SMTP Authentication Error")
+            .reason("Invalid Challenge"),
+        ClientError::UnparseableReply => event.details("Unparseable SMTP Reply"),
+        ClientError::UnexpectedReply(reply) => event
+            .details("Unexpected SMTP Response")
+            .ctx(trc::Key::Code, reply.code)
+            .ctx(trc::Key::Reason, reply.message.clone()),
+        ClientError::AuthenticationFailed(reply) => event
+            .details("SMTP Authentication Failed")
+            .ctx(trc::Key::Code, reply.code)
+            .ctx(trc::Key::Reason, reply.message.clone()),
+        ClientError::InvalidTLSName => event.details("Invalid TLS Name"),
+        ClientError::MissingCredentials => event.details("Missing Authentication Credentials"),
+        ClientError::MissingMailFrom => event.details("Missing Message Sender"),
+        ClientError::MissingRcptTo => event.details("Missing Message Recipients"),
+        ClientError::UnsupportedAuthMechanism => {
+            event.details("Unsupported Authentication Mechanism")
+        }
+        ClientError::Timeout => event.details("Connection Timeout"),
+        ClientError::MissingStartTls => event.details("STARTTLS not available"),
+    }
+}
+
+pub(crate) fn from_error_status(err: &Status<HostResponse<Box<str>>, ErrorDetails>) -> trc::Error {
+    match err {
+        Status::Scheduled | Status::Completed(_) => {
+            trc::EventType::Smtp(trc::SmtpEvent::Error).into_err()
+        }
+        Status::TemporaryFailure(err) | Status::PermanentFailure(err) => {
+            from_error_details(&err.details)
+        }
+    }
+}
+
+pub(crate) fn from_error_details(err: &Error) -> trc::Error {
+    let event = trc::EventType::Smtp(trc::SmtpEvent::Error).into_err();
+    match err {
+        Error::DnsError(err) => event.details("DNS Error").reason(err),
+        Error::UnexpectedResponse(reply) => event
+            .details("Unexpected SMTP Response")
+            .ctx(trc::Key::Code, reply.response.code)
+            .ctx(trc::Key::Details, reply.command.clone())
+            .ctx(trc::Key::Reason, reply.response.message.clone()),
+        Error::ConnectionError(err) => event
+            .details("Connection Error")
+            .ctx(trc::Key::Reason, err.clone()),
+        Error::TlsError(err) => event
+            .details("TLS Error")
+            .ctx(trc::Key::Reason, err.clone()),
+        Error::DaneError(err) => event
+            .details("DANE Error")
+            .ctx(trc::Key::Reason, err.clone()),
+        Error::MtaStsError(err) => event.details("MTA-STS Error").reason(err),
+        Error::RateLimited => event.details("Rate Limited"),
+        Error::ConcurrencyLimited => event.details("Concurrency Limited"),
+        Error::Io(err) => event.details("I/O Error").reason(err),
+    }
+}

crates/smtp/src/outbound/dane/dnssec.rs

@@ -0,0 +1,627 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use common::{
+    Server,
+    config::smtp::resolver::{Tlsa, TlsaEntry, TlsaMatching},
+};
+pub use mail_auth::DnssecStatus;
+use mail_auth::{
+    MX, RecordSet,
+    common::resolver::ToFqdn,
+    hickory_resolver::{
+        net::{DnsError, NetError},
+        proto::{
+            dnssec::Proof,
+            op::ResponseCode,
+            rr::{
+                Name, RData, Record, RecordType,
+                rdata::tlsa::{CertUsage, Matching, Selector},
+            },
+        },
+    },
+};
+use std::{
+    future::Future,
+    net::{Ipv4Addr, Ipv6Addr},
+    sync::Arc,
+    time::{Duration, Instant},
+};
+
+pub trait TlsaLookup: Sync + Send {
+    fn mx_lookup(
+        &self,
+        key: impl ToFqdn + Sync + Send,
+    ) -> impl Future<Output = mail_auth::Result<RecordSet<MX>>> + Send;
+
+    fn tlsa_lookup(
+        &self,
+        key: impl ToFqdn + Sync + Send,
+    ) -> impl Future<Output = mail_auth::Result<TlsaResult>> + Send;
+
+    fn ipv4_lookup_dnssec(
+        &self,
+        key: impl ToFqdn + Sync + Send,
+    ) -> impl Future<Output = mail_auth::Result<RecordSet<Ipv4Addr>>> + Send;
+
+    fn ipv6_lookup_dnssec(
+        &self,
+        key: impl ToFqdn + Sync + Send,
+    ) -> impl Future<Output = mail_auth::Result<RecordSet<Ipv6Addr>>> + Send;
+}
+
+pub enum TlsaResult {
+    Secure(Arc<Tlsa>),
+    Bogus,
+    Missing,
+}
+
+impl TlsaLookup for Server {
+    async fn mx_lookup(&self, key: impl ToFqdn + Sync + Send) -> mail_auth::Result<RecordSet<MX>> {
+        if !self.core.smtp.resolvers.dnssec_available {
+            return self
+                .core
+                .smtp
+                .resolvers
+                .dns
+                .mx_lookup(key, Some(&self.inner.cache.dns_mx))
+                .await;
+        }
+
+        let key = key.to_fqdn().into_owned().into_boxed_str();
+        if let Some(value) = self.inner.cache.dns_mx.get::<str>(key.as_ref())
+            && value.dnssec_status != DnssecStatus::Indeterminate
+        {
+            return Ok(value);
+        }
+
+        #[cfg(any(test, feature = "test_mode"))]
+        if true {
+            return mail_auth::common::resolver::mock_resolve(key.as_ref());
+        }
+
+        let mx_lookup = match self
+            .core
+            .smtp
+            .resolvers
+            .dnssec
+            .resolver
+            .mx_lookup(Name::from_str_relaxed::<&str>(key.as_ref())?)
+            .await
+        {
+            Ok(mx_lookup) => mx_lookup,
+            Err(err) => {
+                if let Some(denial) = NegativeAnswer::from_error(&err)
+                    && denial.response_code == ResponseCode::NoError
+                {
+                    let records = RecordSet {
+                        rrset: Arc::new([]),
+                        dnssec_status: denial.dnssec_status,
+                    };
+                    if let Some(valid_until) = denial.valid_until {
+                        self.inner.cache.dns_mx.insert_with_expiry(
+                            key,
+                            records.clone(),
+                            valid_until,
+                        );
+                    }
+                    return Ok(records);
+                }
+                return Err(err.into());
+            }
+        };
+        let mx_records = mx_lookup.answers();
+        let mut dnssec_status: Option<DnssecStatus> = None;
+        let mut records: Vec<(u16, Vec<Box<str>>)> = Vec::with_capacity(mx_records.len());
+        for mx_record in mx_records {
+            if let RData::MX(mx) = &mx_record.data {
+                dnssec_status = Some(match dnssec_status {
+                    Some(status) => least_secure(status, proof_to_dnssec_status(mx_record.proof)),
+                    None => proof_to_dnssec_status(mx_record.proof),
+                });
+
+                let preference = mx.preference;
+                let exchange = mx.exchange.to_lowercase().to_ascii().into_boxed_str();
+
+                if let Some(record) = records.iter_mut().find(|r| r.0 == preference) {
+                    record.1.push(exchange);
+                } else {
+                    records.push((preference, vec![exchange]));
+                }
+            }
+        }
+
+        records.sort_unstable_by_key(|a| a.0);
+        let rrset: Arc<[MX]> = records
+            .into_iter()
+            .map(|(preference, exchanges)| MX {
+                preference,
+                exchanges: exchanges.into_boxed_slice(),
+            })
+            .collect::<Arc<[MX]>>();
+        let records = RecordSet {
+            rrset,
+            dnssec_status: dnssec_status.unwrap_or(DnssecStatus::Indeterminate),
+        };
+
+        self.inner
+            .cache
+            .dns_mx
+            .insert_with_expiry(key, records.clone(), mx_lookup.valid_until());
+
+        Ok(records)
+    }
+
+    async fn tlsa_lookup(&self, key: impl ToFqdn + Sync + Send) -> mail_auth::Result<TlsaResult> {
+        let key = key.to_fqdn().into_owned().into_boxed_str();
+        if let Some(value) = self.inner.cache.dns_tlsa.get(key.as_ref()) {
+            return Ok(TlsaResult::Secure(value));
+        }
+
+        #[cfg(any(test, feature = "test_mode"))]
+        if true {
+            if key.as_ref().contains("_dnssec_bogus.") {
+                return Ok(TlsaResult::Bogus);
+            }
+            return mail_auth::common::resolver::mock_resolve(key.as_ref());
+        }
+
+        let tlsa_lookup = match self
+            .core
+            .smtp
+            .resolvers
+            .dnssec
+            .resolver
+            .tlsa_lookup(Name::from_str_relaxed(key.as_ref())?)
+            .await
+        {
+            Ok(tlsa_lookup) => tlsa_lookup,
+            Err(err) => {
+                if let Some(denial) = NegativeAnswer::from_error(&err) {
+                    return Ok(if denial.dnssec_status == DnssecStatus::Bogus {
+                        TlsaResult::Bogus
+                    } else {
+                        TlsaResult::Missing
+                    });
+                }
+                return Err(err.into());
+            }
+        };
+
+        let mut entries = Vec::new();
+        let mut has_end_entities = false;
+        let mut has_intermediates = false;
+        let mut dnssec_status: Option<DnssecStatus> = None;
+
+        for record in tlsa_lookup.answers() {
+            if let RData::TLSA(tlsa) = &record.data {
+                dnssec_status = Some(match dnssec_status {
+                    Some(status) => least_secure(status, proof_to_dnssec_status(record.proof)),
+                    None => proof_to_dnssec_status(record.proof),
+                });
+
+                if !record.proof.is_secure() {
+                    continue;
+                }
+
+                let is_end_entity = match tlsa.cert_usage {
+                    CertUsage::DaneEe => true,
+                    CertUsage::DaneTa => false,
+                    _ => continue,
+                };
+                let matching = match tlsa.matching {
+                    Matching::Raw => TlsaMatching::Full,
+                    Matching::Sha256 => TlsaMatching::Sha256,
+                    Matching::Sha512 => TlsaMatching::Sha512,
+                    _ => continue,
+                };
+                let is_spki = match tlsa.selector {
+                    Selector::Spki => true,
+                    Selector::Full => false,
+                    _ => continue,
+                };
+                if is_end_entity {
+                    has_end_entities = true;
+                } else {
+                    has_intermediates = true;
+                }
+                entries.push(TlsaEntry {
+                    is_end_entity,
+                    is_spki,
+                    matching,
+                    data: tlsa.cert_data.clone(),
+                });
+            }
+        }
+
+        match dnssec_status {
+            Some(DnssecStatus::Bogus) => Ok(TlsaResult::Bogus),
+            Some(DnssecStatus::Secure) => {
+                let tlsa = Arc::new(Tlsa {
+                    entries,
+                    has_end_entities,
+                    has_intermediates,
+                });
+
+                self.inner.cache.dns_tlsa.insert_with_expiry(
+                    key,
+                    tlsa.clone(),
+                    tlsa_lookup.valid_until(),
+                );
+
+                Ok(TlsaResult::Secure(tlsa))
+            }
+            _ => Ok(TlsaResult::Missing),
+        }
+    }
+
+    async fn ipv4_lookup_dnssec(
+        &self,
+        key: impl ToFqdn + Sync + Send,
+    ) -> mail_auth::Result<RecordSet<Ipv4Addr>> {
+        if !self.core.smtp.resolvers.dnssec_available {
+            return self
+                .core
+                .smtp
+                .resolvers
+                .dns
+                .ipv4_lookup(key, Some(&self.inner.cache.dns_ipv4))
+                .await;
+        }
+
+        let key = key.to_fqdn().into_owned().into_boxed_str();
+        if let Some(value) = self.inner.cache.dns_ipv4.get::<str>(key.as_ref())
+            && value.dnssec_status != DnssecStatus::Indeterminate
+        {
+            return Ok(value);
+        }
+
+        #[cfg(any(test, feature = "test_mode"))]
+        if true {
+            return mail_auth::common::resolver::mock_resolve(key.as_ref());
+        }
+
+        let name = Name::from_str_relaxed::<&str>(key.as_ref())?;
+        let lookup = match self
+            .core
+            .smtp
+            .resolvers
+            .dnssec
+            .resolver
+            .ipv4_lookup(name.clone())
+            .await
+        {
+            Ok(lookup) => lookup,
+            Err(err) => {
+                if let Some(denial) = NegativeAnswer::from_error(&err)
+                    && denial.response_code == ResponseCode::NoError
+                {
+                    let records = RecordSet {
+                        rrset: Arc::new([]),
+                        dnssec_status: denial.dnssec_status,
+                    };
+                    if let Some(valid_until) = denial.valid_until {
+                        self.inner.cache.dns_ipv4.insert_with_expiry(
+                            key,
+                            records.clone(),
+                            valid_until,
+                        );
+                    }
+                    return Ok(records);
+                }
+                return Err(err.into());
+            }
+        };
+
+        let answers = lookup.answers();
+        let records = RecordSet {
+            rrset: answers
+                .iter()
+                .filter_map(|record| match &record.data {
+                    RData::A(addr) => Some(addr.0),
+                    _ => None,
+                })
+                .collect::<Arc<[Ipv4Addr]>>(),
+            dnssec_status: tlsa_base_status(&name, answers, RecordType::A),
+        };
+
+        self.inner
+            .cache
+            .dns_ipv4
+            .insert_with_expiry(key, records.clone(), lookup.valid_until());
+
+        Ok(records)
+    }
+
+    async fn ipv6_lookup_dnssec(
+        &self,
+        key: impl ToFqdn + Sync + Send,
+    ) -> mail_auth::Result<RecordSet<Ipv6Addr>> {
+        if !self.core.smtp.resolvers.dnssec_available {
+            return self
+                .core
+                .smtp
+                .resolvers
+                .dns
+                .ipv6_lookup(key, Some(&self.inner.cache.dns_ipv6))
+                .await;
+        }
+
+        let key = key.to_fqdn().into_owned().into_boxed_str();
+        if let Some(value) = self.inner.cache.dns_ipv6.get::<str>(key.as_ref())
+            && value.dnssec_status != DnssecStatus::Indeterminate
+        {
+            return Ok(value);
+        }
+
+        #[cfg(any(test, feature = "test_mode"))]
+        if true {
+            return mail_auth::common::resolver::mock_resolve(key.as_ref());
+        }
+
+        let name = Name::from_str_relaxed::<&str>(key.as_ref())?;
+        let lookup = match self
+            .core
+            .smtp
+            .resolvers
+            .dnssec
+            .resolver
+            .ipv6_lookup(name.clone())
+            .await
+        {
+            Ok(lookup) => lookup,
+            Err(err) => {
+                if let Some(denial) = NegativeAnswer::from_error(&err)
+                    && denial.response_code == ResponseCode::NoError
+                {
+                    let records = RecordSet {
+                        rrset: Arc::new([]),
+                        dnssec_status: denial.dnssec_status,
+                    };
+                    if let Some(valid_until) = denial.valid_until {
+                        self.inner.cache.dns_ipv6.insert_with_expiry(
+                            key,
+                            records.clone(),
+                            valid_until,
+                        );
+                    }
+                    return Ok(records);
+                }
+                return Err(err.into());
+            }
+        };
+
+        let answers = lookup.answers();
+        let records = RecordSet {
+            rrset: answers
+                .iter()
+                .filter_map(|record| match &record.data {
+                    RData::AAAA(addr) => Some(addr.0),
+                    _ => None,
+                })
+                .collect::<Arc<[Ipv6Addr]>>(),
+            dnssec_status: tlsa_base_status(&name, answers, RecordType::AAAA),
+        };
+
+        self.inner
+            .cache
+            .dns_ipv6
+            .insert_with_expiry(key, records.clone(), lookup.valid_until());
+
+        Ok(records)
+    }
+}
+
+struct NegativeAnswer {
+    response_code: ResponseCode,
+    dnssec_status: DnssecStatus,
+    valid_until: Option<Instant>,
+}
+
+impl NegativeAnswer {
+    fn from_error(err: &NetError) -> Option<Self> {
+        let NetError::Dns(dns_error) = err else {
+            return None;
+        };
+
+        match dns_error {
+            DnsError::NoRecordsFound(no_records) => Some(NegativeAnswer {
+                response_code: no_records.response_code,
+                dnssec_status: no_records
+                    .authorities
+                    .as_deref()
+                    .map(denial_dnssec_status)
+                    .unwrap_or(DnssecStatus::Indeterminate),
+                valid_until: no_records
+                    .negative_ttl
+                    .map(|ttl| Instant::now() + Duration::from_secs(ttl as u64)),
+            }),
+            DnsError::Nsec {
+                response, proof, ..
+            } => Some(NegativeAnswer {
+                response_code: response.response_code,
+                dnssec_status: proof_to_dnssec_status(*proof),
+                valid_until: None,
+            }),
+            _ => None,
+        }
+    }
+}
+
+fn denial_dnssec_status(authorities: &[Record]) -> DnssecStatus {
+    authorities
+        .iter()
+        .filter(|record| matches!(record.record_type(), RecordType::NSEC | RecordType::NSEC3))
+        .map(|record| proof_to_dnssec_status(record.proof))
+        .reduce(least_secure)
+        .unwrap_or(DnssecStatus::Indeterminate)
+}
+
+fn proof_to_dnssec_status(proof: Proof) -> DnssecStatus {
+    match proof {
+        Proof::Secure => DnssecStatus::Secure,
+        Proof::Insecure => DnssecStatus::Insecure,
+        Proof::Bogus => DnssecStatus::Bogus,
+        Proof::Indeterminate => DnssecStatus::Indeterminate,
+    }
+}
+
+fn tlsa_base_status(query: &Name, answers: &[Record], address_type: RecordType) -> DnssecStatus {
+    let mut addresses: Option<DnssecStatus> = None;
+    let mut alias: Option<DnssecStatus> = None;
+
+    for record in answers {
+        let status = proof_to_dnssec_status(record.proof);
+        if record.record_type() == address_type {
+            addresses = Some(match addresses {
+                Some(current) => least_secure(current, status),
+                None => status,
+            });
+        } else if record.record_type() == RecordType::CNAME && &record.name == query {
+            alias = Some(match alias {
+                Some(current) => least_secure(current, status),
+                None => status,
+            });
+        }
+    }
+
+    match (addresses, alias) {
+        (Some(DnssecStatus::Insecure), Some(DnssecStatus::Secure)) => DnssecStatus::Secure,
+        (Some(status), _) => status,
+        (None, _) => DnssecStatus::Indeterminate,
+    }
+}
+
+pub(crate) fn least_secure(a: DnssecStatus, b: DnssecStatus) -> DnssecStatus {
+    fn rank(status: DnssecStatus) -> u8 {
+        match status {
+            DnssecStatus::Bogus => 0,
+            DnssecStatus::Indeterminate => 1,
+            DnssecStatus::Insecure => 2,
+            DnssecStatus::Secure => 3,
+        }
+    }
+
+    if rank(a) <= rank(b) { a } else { b }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use mail_auth::hickory_resolver::proto::rr::rdata::{A, CNAME};
+    use std::net::Ipv4Addr;
+
+    fn name(value: &str) -> Name {
+        Name::from_ascii(value).unwrap()
+    }
+
+    fn address(owner: &str, proof: Proof) -> Record {
+        let mut record =
+            Record::from_rdata(name(owner), 3600, RData::A(A(Ipv4Addr::new(192, 0, 2, 1))));
+        record.proof = proof;
+        record
+    }
+
+    fn alias(owner: &str, target: &str, proof: Proof) -> Record {
+        let mut record = Record::from_rdata(name(owner), 3600, RData::CNAME(CNAME(name(target))));
+        record.proof = proof;
+        record
+    }
+
+    #[test]
+    fn tlsa_base_status_follows_address_records() {
+        let query = name("mx.example.org.");
+
+        for (proof, expected) in [
+            (Proof::Secure, DnssecStatus::Secure),
+            (Proof::Insecure, DnssecStatus::Insecure),
+            (Proof::Bogus, DnssecStatus::Bogus),
+            (Proof::Indeterminate, DnssecStatus::Indeterminate),
+        ] {
+            assert_eq!(
+                tlsa_base_status(&query, &[address("mx.example.org.", proof)], RecordType::A),
+                expected,
+                "proof {proof}"
+            );
+        }
+    }
+
+    #[test]
+    fn tlsa_base_status_is_indeterminate_without_addresses() {
+        assert_eq!(
+            tlsa_base_status(&name("mx.example.org."), &[], RecordType::A),
+            DnssecStatus::Indeterminate
+        );
+    }
+
+    #[test]
+    fn tlsa_base_status_takes_least_secure_address() {
+        let query = name("mx.example.org.");
+
+        assert_eq!(
+            tlsa_base_status(
+                &query,
+                &[
+                    address("mx.example.org.", Proof::Secure),
+                    address("mx.example.org.", Proof::Insecure),
+                ],
+                RecordType::A
+            ),
+            DnssecStatus::Insecure
+        );
+    }
+
+    #[test]
+    fn tlsa_base_status_keeps_secure_alias_to_insecure_zone() {
+        let query = name("mx.example.org.");
+
+        assert_eq!(
+            tlsa_base_status(
+                &query,
+                &[
+                    alias("mx.example.org.", "mx.provider.net.", Proof::Secure),
+                    address("mx.provider.net.", Proof::Insecure),
+                ],
+                RecordType::A
+            ),
+            DnssecStatus::Secure
+        );
+    }
+
+    #[test]
+    fn tlsa_base_status_skips_insecure_alias() {
+        let query = name("mx.example.org.");
+
+        assert_eq!(
+            tlsa_base_status(
+                &query,
+                &[
+                    alias("mx.example.org.", "mx.provider.net.", Proof::Insecure),
+                    address("mx.provider.net.", Proof::Insecure),
+                ],
+                RecordType::A
+            ),
+            DnssecStatus::Insecure
+        );
+    }
+
+    #[test]
+    fn tlsa_base_status_ignores_alias_below_query_name() {
+        let query = name("mx.example.org.");
+
+        assert_eq!(
+            tlsa_base_status(
+                &query,
+                &[
+                    alias("mx.provider.net.", "mx.other.net.", Proof::Secure),
+                    address("mx.other.net.", Proof::Insecure),
+                ],
+                RecordType::A
+            ),
+            DnssecStatus::Insecure
+        );
+    }
+}

crates/smtp/src/outbound/dane/mod.rs

@@ -0,0 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+pub mod dnssec;
+pub mod verify;

crates/smtp/src/outbound/dane/verify.rs

@@ -0,0 +1,242 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use crate::queue::{Error, ErrorDetails, HostResponse, Status};
+use common::config::smtp::resolver::{Tlsa, TlsaEntry, TlsaMatching};
+use rustls_pki_types::{CertificateDer, Der, ServerName, TrustAnchor, UnixTime};
+use sha2::{Digest, Sha256, Sha512};
+use trc::DaneEvent;
+use webpki::{ALL_VERIFICATION_ALGS, EndEntityCert, KeyUsage, anchor_from_trusted_cert};
+use x509_parser::asn1_rs::Any;
+use x509_parser::prelude::{FromDer, X509Certificate};
+
+pub trait TlsaVerify {
+    fn verify(
+        &self,
+        session_id: u64,
+        hostname: &str,
+        reference_ids: &[&str],
+        certificates: Option<&[CertificateDer<'_>]>,
+    ) -> Result<(), Status<HostResponse<Box<str>>, ErrorDetails>>;
+}
+
+impl TlsaVerify for Tlsa {
+    fn verify(
+        &self,
+        session_id: u64,
+        hostname: &str,
+        reference_ids: &[&str],
+        certificates: Option<&[CertificateDer<'_>]>,
+    ) -> Result<(), Status<HostResponse<Box<str>>, ErrorDetails>> {
+        let certificates = match certificates {
+            Some(certificates) if !certificates.is_empty() => certificates,
+            _ => {
+                trc::event!(
+                    Dane(DaneEvent::NoCertificatesFound),
+                    SpanId = session_id,
+                    Hostname = hostname.to_string(),
+                );
+
+                return Err(Status::TemporaryFailure(ErrorDetails {
+                    entity: hostname.into(),
+                    details: Error::DaneError("No certificates were provided by host".into()),
+                }));
+            }
+        };
+
+        let mut parsed = Vec::with_capacity(certificates.len());
+        for der_certificate in certificates {
+            match X509Certificate::from_der(der_certificate.as_ref()) {
+                Ok((_, cert)) => parsed.push(cert),
+                Err(err) => {
+                    trc::event!(
+                        Dane(DaneEvent::CertificateParseError),
+                        SpanId = session_id,
+                        Hostname = hostname.to_string(),
+                        Reason = err.to_string(),
+                    );
+
+                    return Err(Status::TemporaryFailure(ErrorDetails {
+                        entity: hostname.into(),
+                        details: Error::DaneError("Failed to parse X.509 certificate".into()),
+                    }));
+                }
+            }
+        }
+
+        if verify_end_entity(self, session_id, hostname, certificates, &parsed)
+            || verify_trust_anchor(
+                self,
+                session_id,
+                hostname,
+                reference_ids,
+                certificates,
+                &parsed,
+            )
+        {
+            trc::event!(
+                Dane(DaneEvent::AuthenticationSuccess),
+                SpanId = session_id,
+                Hostname = hostname.to_string(),
+            );
+
+            Ok(())
+        } else {
+            trc::event!(
+                Dane(DaneEvent::AuthenticationFailure),
+                SpanId = session_id,
+                Hostname = hostname.to_string(),
+            );
+
+            Err(Status::TemporaryFailure(ErrorDetails {
+                entity: hostname.into(),
+                details: Error::DaneError("No matching certificates found in TLSA records".into()),
+            }))
+        }
+    }
+}
+
+fn verify_end_entity(
+    tlsa: &Tlsa,
+    session_id: u64,
+    hostname: &str,
+    certificates: &[CertificateDer<'_>],
+    parsed: &[X509Certificate<'_>],
+) -> bool {
+    if tlsa.has_end_entities {
+        for record in tlsa.entries.iter().filter(|record| record.is_end_entity) {
+            if record_matches(record, &parsed[0], certificates[0].as_ref()) {
+                trc::event!(
+                    Dane(DaneEvent::TlsaRecordMatch),
+                    SpanId = session_id,
+                    Hostname = hostname.to_string(),
+                    Type = "end-entity",
+                );
+                return true;
+            }
+        }
+    }
+
+    false
+}
+
+fn verify_trust_anchor(
+    tlsa: &Tlsa,
+    session_id: u64,
+    hostname: &str,
+    reference_ids: &[&str],
+    certificates: &[CertificateDer<'_>],
+    parsed: &[X509Certificate<'_>],
+) -> bool {
+    if !tlsa.has_intermediates {
+        return false;
+    }
+
+    let end_entity = match EndEntityCert::try_from(&certificates[0]) {
+        Ok(end_entity) => end_entity,
+        Err(_) => return false,
+    };
+
+    let mut anchors: Vec<TrustAnchor<'static>> = Vec::new();
+
+    for record in tlsa.entries.iter().filter(|record| !record.is_end_entity) {
+        match (record.is_spki, record.matching) {
+            (false, TlsaMatching::Full) => {
+                let der = CertificateDer::from(record.data.clone());
+                if let Ok(anchor) = anchor_from_trusted_cert(&der) {
+                    anchors.push(anchor.to_owned());
+                }
+            }
+            (true, TlsaMatching::Full) => {
+                if let Some(depth) = (1..certificates.len())
+                    .find(|&depth| parsed[depth].public_key().raw == record.data.as_slice())
+                {
+                    if let Ok(anchor) = anchor_from_trusted_cert(&certificates[depth]) {
+                        anchors.push(anchor.to_owned());
+                    }
+                } else if let Some(spki) = der_value(&record.data) {
+                    for depth in 1..certificates.len() {
+                        if is_chain_top(parsed, depth)
+                            && let Some(subject) = der_value(parsed[depth].issuer().as_raw())
+                        {
+                            anchors.push(TrustAnchor {
+                                subject: Der::from(subject.to_vec()),
+                                subject_public_key_info: Der::from(spki.to_vec()),
+                                name_constraints: None,
+                            });
+                        }
+                    }
+                }
+            }
+            _ => {
+                for depth in 1..certificates.len() {
+                    if record_matches(record, &parsed[depth], certificates[depth].as_ref())
+                        && let Ok(anchor) = anchor_from_trusted_cert(&certificates[depth])
+                    {
+                        anchors.push(anchor.to_owned());
+                    }
+                }
+            }
+        }
+    }
+
+    if anchors.is_empty()
+        || end_entity
+            .verify_for_usage(
+                ALL_VERIFICATION_ALGS,
+                &anchors,
+                &certificates[1..],
+                UnixTime::now(),
+                KeyUsage::server_auth(),
+                None,
+                None,
+            )
+            .is_err()
+        || !reference_ids.iter().any(|reference| {
+            ServerName::try_from(*reference)
+                .map(|name| end_entity.verify_is_valid_for_subject_name(&name).is_ok())
+                .unwrap_or(false)
+        })
+    {
+        false
+    } else {
+        trc::event!(
+            Dane(DaneEvent::TlsaRecordMatch),
+            SpanId = session_id,
+            Hostname = hostname.to_string(),
+            Type = "trust-anchor",
+        );
+
+        true
+    }
+}
+
+fn is_chain_top(parsed: &[X509Certificate<'_>], depth: usize) -> bool {
+    let issuer = parsed[depth].issuer().as_raw();
+    !parsed
+        .iter()
+        .enumerate()
+        .any(|(other, cert)| other != depth && cert.subject().as_raw() == issuer)
+}
+
+fn record_matches(record: &TlsaEntry, cert: &X509Certificate<'_>, raw: &[u8]) -> bool {
+    let selected: &[u8] = if record.is_spki {
+        cert.public_key().raw
+    } else {
+        raw
+    };
+
+    match record.matching {
+        TlsaMatching::Full => selected == record.data.as_slice(),
+        TlsaMatching::Sha256 => Sha256::digest(selected).as_slice() == record.data.as_slice(),
+        TlsaMatching::Sha512 => Sha512::digest(selected).as_slice() == record.data.as_slice(),
+    }
+}
+
+#[inline(always)]
+fn der_value(der: &[u8]) -> Option<&[u8]> {
+    Any::from_der(der).ok().map(|(_, any)| any.data)
+}

crates/smtp/src/outbound/error.rs

@@ -0,0 +1,150 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use std::fmt::Display;
+
+use smtp_proto::{Response, Severity};
+
+#[derive(Debug)]
+pub enum ClientError {
+    /// I/O error
+    Io(std::io::Error),
+
+    /// TLS error
+    Tls(Box<rustls::Error>),
+
+    /// Base64 decode error
+    Base64(base64::DecodeError),
+
+    // SMTP authentication error.
+    InvalidChallenge,
+
+    /// Failure parsing SMTP reply
+    UnparseableReply,
+
+    /// Unexpected SMTP reply.
+    UnexpectedReply(Box<smtp_proto::Response<String>>),
+
+    /// SMTP authentication failure.
+    AuthenticationFailed(Box<smtp_proto::Response<String>>),
+
+    /// Invalid TLS name provided.
+    InvalidTLSName,
+
+    /// Missing authentication credentials.
+    MissingCredentials,
+
+    /// Missing message sender.
+    MissingMailFrom,
+
+    /// Missing message recipients.
+    MissingRcptTo,
+
+    /// The server does no support any of the available authentication methods.
+    UnsupportedAuthMechanism,
+
+    /// Connection timeout.
+    Timeout,
+
+    /// STARTTLS not available
+    MissingStartTls,
+}
+
+pub trait AssertReply: Sized {
+    fn is_positive_completion(&self) -> bool;
+    fn assert_positive_completion(self) -> ClientResult<()>;
+    fn assert_severity(self, severity: Severity) -> ClientResult<()>;
+    fn assert_code(self, code: u16) -> ClientResult<()>;
+}
+
+impl AssertReply for Response<String> {
+    /// Returns `true` if the reply is a positive completion.
+    #[inline(always)]
+    fn is_positive_completion(&self) -> bool {
+        (200..=299).contains(&self.code)
+    }
+
+    /// Returns Ok if the reply has the specified severity.
+    #[inline(always)]
+    fn assert_severity(self, severity: Severity) -> ClientResult<()> {
+        if self.severity() == severity {
+            Ok(())
+        } else {
+            Err(ClientError::UnexpectedReply(Box::new(self)))
+        }
+    }
+
+    /// Returns Ok if the reply returned a 2xx code.
+    #[inline(always)]
+    fn assert_positive_completion(self) -> ClientResult<()> {
+        if (200..=299).contains(&self.code) {
+            Ok(())
+        } else {
+            Err(ClientError::UnexpectedReply(Box::new(self)))
+        }
+    }
+
+    /// Returns Ok if the reply has the specified status code.
+    #[inline(always)]
+    fn assert_code(self, code: u16) -> ClientResult<()> {
+        if self.code() == code {
+            Ok(())
+        } else {
+            Err(ClientError::UnexpectedReply(Box::new(self)))
+        }
+    }
+}
+
+impl std::error::Error for ClientError {
+    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
+        match self {
+            ClientError::Io(err) => err.source(),
+            ClientError::Tls(err) => err.source(),
+            ClientError::Base64(err) => err.source(),
+            _ => None,
+        }
+    }
+}
+
+pub type ClientResult<T> = std::result::Result<T, ClientError>;
+
+impl Display for ClientError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            ClientError::Io(e) => write!(f, "I/O error: {e}"),
+            ClientError::Tls(e) => write!(f, "TLS error: {e}"),
+            ClientError::Base64(e) => write!(f, "Base64 decode error: {e}"),
+            ClientError::InvalidChallenge => {
+                write!(f, "SMTP authentication error: Invalid challenge")
+            }
+            ClientError::UnparseableReply => write!(f, "Unparseable SMTP reply"),
+            ClientError::UnexpectedReply(e) => write!(f, "Unexpected reply: {e}"),
+            ClientError::AuthenticationFailed(e) => write!(f, "Authentication failed: {e}"),
+            ClientError::InvalidTLSName => write!(f, "Invalid TLS name provided"),
+            ClientError::MissingCredentials => write!(f, "Missing authentication credentials"),
+            ClientError::MissingMailFrom => write!(f, "Missing message sender"),
+            ClientError::MissingRcptTo => write!(f, "Missing message recipients"),
+            ClientError::UnsupportedAuthMechanism => write!(
+                f,
+                "The server does no support any of the available authentication methods"
+            ),
+            ClientError::Timeout => write!(f, "Connection timeout"),
+            ClientError::MissingStartTls => write!(f, "STARTTLS extension unavailable"),
+        }
+    }
+}
+
+impl From<std::io::Error> for ClientError {
+    fn from(err: std::io::Error) -> Self {
+        ClientError::Io(err)
+    }
+}
+
+impl From<base64::DecodeError> for ClientError {
+    fn from(err: base64::DecodeError) -> Self {
+        ClientError::Base64(err)
+    }
+}

crates/smtp/src/outbound/local.rs

@@ -0,0 +1,145 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use crate::{
+    inbound::dkim::DkimSign,
+    outbound::DeliveryResult,
+    queue::{
+        Error, ErrorDetails, FROM_AUTHENTICATED, FROM_UNAUTHENTICATED_DMARC, HostResponse,
+        MessageSource, MessageWrapper, Status, UnexpectedResponse,
+        quota::HasQueueQuota,
+        rcpt_spam_percentage,
+        spool::{QueueParams, SmtpSpool},
+    },
+};
+use common::Server;
+use email::message::delivery::{IngestMessage, IngestRecipient, LocalDeliveryStatus, MailDelivery};
+use smtp_proto::Response;
+use trc::SieveEvent;
+
+impl MessageWrapper {
+    pub(super) async fn deliver_local(
+        &self,
+        rcpt_idxs: &[usize],
+        statuses: &mut Vec<DeliveryResult>,
+        server: &Server,
+    ) {
+        // Prepare recipients list
+        let mut pending_recipients = Vec::new();
+        let mut recipients = Vec::new();
+        for &rcpt_idx in rcpt_idxs {
+            let rcpt = &self.message.recipients[rcpt_idx];
+            let rcpt_addr = rcpt.address();
+            recipients.push(IngestRecipient {
+                address: rcpt_addr.to_lowercase(),
+                orcpt: rcpt.orcpt.as_ref().map(|orcpt| orcpt.to_string()),
+                spam_percentage: rcpt_spam_percentage(rcpt.flags),
+            });
+            pending_recipients.push((rcpt_idx, rcpt_addr));
+        }
+
+        // Deliver message
+        let delivery_result = server
+            .deliver_message(IngestMessage {
+                sender_address: self.message.return_path.to_string(),
+                sender_authenticated: self.message.flags
+                    & (FROM_UNAUTHENTICATED_DMARC | FROM_AUTHENTICATED)
+                    != 0,
+                recipients,
+                message_blob: self.message.blob_hash.clone(),
+                message_size: self.message.size,
+                session_id: self.span_id,
+            })
+            .await;
+
+        // Process delivery results
+        for ((rcpt_idx, rcpt_addr), result) in
+            pending_recipients.into_iter().zip(delivery_result.status)
+        {
+            let status = match result {
+                LocalDeliveryStatus::Success => Status::Completed(HostResponse {
+                    hostname: "localhost".into(),
+                    response: Response {
+                        code: 250,
+                        esc: [2, 1, 5],
+                        message: "OK".into(),
+                    },
+                }),
+                LocalDeliveryStatus::TemporaryFailure { reason } => {
+                    Status::TemporaryFailure(ErrorDetails {
+                        entity: "localhost".into(),
+                        details: Error::UnexpectedResponse(UnexpectedResponse {
+                            command: format!("RCPT TO:<{rcpt_addr}>").into_boxed_str(),
+                            response: Response {
+                                code: 451,
+                                esc: [4, 3, 0],
+                                message: reason.into(),
+                            },
+                        }),
+                    })
+                }
+                LocalDeliveryStatus::PermanentFailure { code, reason } => {
+                    Status::PermanentFailure(ErrorDetails {
+                        entity: "localhost".into(),
+                        details: Error::UnexpectedResponse(UnexpectedResponse {
+                            command: format!("RCPT TO:<{rcpt_addr}>").into_boxed_str(),
+                            response: Response {
+                                code: 550,
+                                esc: code,
+                                message: reason.into(),
+                            },
+                        }),
+                    })
+                }
+            };
+            statuses.push(DeliveryResult::account(status, rcpt_idx));
+        }
+
+        // Process autogenerated messages
+        for autogenerated in delivery_result.autogenerated {
+            let mut message = server.new_message(
+                autogenerated.sender_address,
+                MessageSource::Autogenerated,
+                self.span_id,
+            );
+            for rcpt in autogenerated.recipients {
+                message.expand_and_add_recipient(rcpt, server).await;
+            }
+
+            // Queue Message
+            message.message.size = autogenerated.message.len() as u64;
+            if let Some(metadata) = server.has_quota(&mut message).await {
+                let dkim_signers = server
+                    .eval_signers(
+                        &server.core.sieve.untrusted_sign,
+                        &message.message,
+                        self.span_id,
+                    )
+                    .await;
+
+                message
+                    .queue(
+                        QueueParams::new(&autogenerated.message, self.span_id, server)
+                            .with_dkim_signers(dkim_signers)
+                            .with_metadata(metadata),
+                    )
+                    .await;
+            } else {
+                trc::event!(
+                    Sieve(SieveEvent::QuotaExceeded),
+                    SpanId = self.span_id,
+                    From = message.message.return_path,
+                    To = message
+                        .message
+                        .recipients
+                        .into_iter()
+                        .map(|r| trc::Value::from(r.address().to_string()))
+                        .collect::<Vec<_>>(),
+                );
+            }
+        }
+    }
+}

crates/smtp/src/outbound/lookup.rs

@@ -0,0 +1,296 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use super::NextHop;
+use super::dane::dnssec::{TlsaLookup, least_secure};
+use crate::queue::{Error, ErrorDetails, HostResponse, Status};
+use common::{
+    Server,
+    config::smtp::queue::{ConnectionStrategy, HostOrIp, IpAndHost, MxConfig},
+    expr::functions::ResolveVariable,
+};
+use mail_auth::{DnssecStatus, IpLookupStrategy, MX, RecordSet};
+use rand::{RngExt, seq::SliceRandom};
+use registry::schema::enums::ExpressionVariable;
+use std::{future::Future, net::IpAddr, sync::Arc};
+
+pub struct ResolvedHost {
+    pub ips: Vec<IpAddr>,
+    pub dnssec_status: DnssecStatus,
+}
+
+pub trait DnsLookup: Sync + Send {
+    fn ip_lookup(
+        &self,
+        key: &str,
+        strategy: IpLookupStrategy,
+        max_results: usize,
+        dnssec: bool,
+    ) -> impl Future<Output = mail_auth::Result<(Vec<IpAddr>, DnssecStatus)>> + Send;
+
+    fn resolve_host(
+        &self,
+        remote_host: &NextHop<'_>,
+        envelope: &impl ResolveVariable,
+        dnssec: bool,
+    ) -> impl Future<Output = Result<ResolvedHost, Status<HostResponse<Box<str>>, ErrorDetails>>> + Send;
+}
+
+impl DnsLookup for Server {
+    async fn ip_lookup(
+        &self,
+        key: &str,
+        strategy: IpLookupStrategy,
+        max_results: usize,
+        dnssec: bool,
+    ) -> mail_auth::Result<(Vec<IpAddr>, DnssecStatus)> {
+        let (has_ipv4, has_ipv6, v4_first) = match strategy {
+            IpLookupStrategy::Ipv4Only => (true, false, false),
+            IpLookupStrategy::Ipv6Only => (false, true, false),
+            IpLookupStrategy::Ipv4thenIpv6 => (true, true, true),
+            IpLookupStrategy::Ipv6thenIpv4 => (true, true, false),
+        };
+        let mut dnssec_status: Option<DnssecStatus> = None;
+
+        let ipv4_addrs = if has_ipv4 {
+            let result = if dnssec {
+                self.ipv4_lookup_dnssec(key).await
+            } else {
+                self.core
+                    .smtp
+                    .resolvers
+                    .dns
+                    .ipv4_lookup(key, Some(&self.inner.cache.dns_ipv4))
+                    .await
+            };
+
+            match result {
+                Ok(addrs) => {
+                    if !addrs.rrset.is_empty() {
+                        dnssec_status = Some(addrs.dnssec_status);
+                    }
+                    addrs.rrset
+                }
+                Err(_) if has_ipv6 => Arc::new([]),
+                Err(err) => return Err(err),
+            }
+        } else {
+            Arc::new([])
+        };
+
+        let ipv6_addrs = if has_ipv6 {
+            let result = if dnssec {
+                self.ipv6_lookup_dnssec(key).await
+            } else {
+                self.core
+                    .smtp
+                    .resolvers
+                    .dns
+                    .ipv6_lookup(key, Some(&self.inner.cache.dns_ipv6))
+                    .await
+            };
+
+            match result {
+                Ok(addrs) => {
+                    if !addrs.rrset.is_empty() {
+                        dnssec_status = Some(match dnssec_status {
+                            Some(status) => least_secure(status, addrs.dnssec_status),
+                            None => addrs.dnssec_status,
+                        });
+                    }
+                    addrs.rrset
+                }
+                Err(_) if !ipv4_addrs.is_empty() => Arc::new([]),
+                Err(err) => return Err(err),
+            }
+        } else {
+            Arc::new([])
+        };
+
+        let remote_ips = if v4_first {
+            ipv4_addrs
+                .iter()
+                .copied()
+                .map(IpAddr::from)
+                .chain(ipv6_addrs.iter().copied().map(IpAddr::from))
+                .take(max_results)
+                .collect()
+        } else {
+            ipv6_addrs
+                .iter()
+                .copied()
+                .map(IpAddr::from)
+                .chain(ipv4_addrs.iter().copied().map(IpAddr::from))
+                .take(max_results)
+                .collect()
+        };
+
+        Ok((
+            remote_ips,
+            dnssec_status.unwrap_or(DnssecStatus::Indeterminate),
+        ))
+    }
+
+    async fn resolve_host(
+        &self,
+        remote_host: &NextHop<'_>,
+        envelope: &impl ResolveVariable,
+        dnssec: bool,
+    ) -> Result<ResolvedHost, Status<HostResponse<Box<str>>, ErrorDetails>> {
+        let (mut remote_ips, dnssec_status) = match remote_host.fqdn_hostname() {
+            HostOrIp::Host(hostname) => self
+                .ip_lookup(
+                    hostname.as_ref(),
+                    remote_host.ip_lookup_strategy(),
+                    remote_host.max_multi_homed(),
+                    dnssec,
+                )
+                .await
+                .map_err(|err| {
+                    if let mail_auth::Error::Dns(mail_auth::DnsError::RecordNotFound(_)) = &err {
+                        if matches!(
+                            remote_host,
+                            NextHop::MX {
+                                is_implicit: true,
+                                ..
+                            }
+                        ) {
+                            Status::PermanentFailure(ErrorDetails {
+                                entity: remote_host.hostname().into(),
+                                details: Error::DnsError("no MX record found.".into()),
+                            })
+                        } else {
+                            Status::PermanentFailure(ErrorDetails {
+                                entity: remote_host.hostname().into(),
+                                details: Error::ConnectionError("record not found for MX".into()),
+                            })
+                        }
+                    } else {
+                        Status::TemporaryFailure(ErrorDetails {
+                            entity: remote_host.hostname().into(),
+                            details: Error::ConnectionError(
+                                format!("lookup error: {err}").into_boxed_str(),
+                            ),
+                        })
+                    }
+                })?,
+            HostOrIp::Ip(ip) => (vec![ip], DnssecStatus::Indeterminate),
+        };
+
+        if !remote_ips.is_empty() {
+            if !remote_host.allow_loopback() && remote_ips.iter().any(|ip| ip.is_loopback()) {
+                remote_ips.retain(|ip| !ip.is_loopback());
+                if remote_ips.is_empty() {
+                    return Err(Status::PermanentFailure(ErrorDetails {
+                        entity: remote_host.hostname().into(),
+                        details: Error::ConnectionError("host resolves loopback address".into()),
+                    }));
+                }
+            }
+
+            Ok(ResolvedHost {
+                ips: remote_ips,
+                dnssec_status,
+            })
+        } else {
+            Err(Status::TemporaryFailure(ErrorDetails {
+                entity: remote_host.hostname().into(),
+                details: Error::DnsError(
+                    format!(
+                        "No IP addresses found for {:?}.",
+                        envelope
+                            .resolve_variable(ExpressionVariable::Mx)
+                            .to_string()
+                    )
+                    .into_boxed_str(),
+                ),
+            }))
+        }
+    }
+}
+
+pub trait SourceIp {
+    fn source_ip(&self, is_v4: bool) -> Option<&IpAndHost>;
+}
+
+impl SourceIp for ConnectionStrategy {
+    fn source_ip(&self, is_v4: bool) -> Option<&IpAndHost> {
+        let ips = if is_v4 {
+            &self.source_ipv4
+        } else {
+            &self.source_ipv6
+        };
+        match ips.len().cmp(&1) {
+            std::cmp::Ordering::Equal => ips.first(),
+            std::cmp::Ordering::Greater => Some(&ips[rand::rng().random_range(0..ips.len())]),
+            std::cmp::Ordering::Less => None,
+        }
+    }
+}
+
+pub trait ToNextHop {
+    fn to_remote_hosts<'x, 'y: 'x>(
+        &'x self,
+        domain: &'y str,
+        config: &'x MxConfig,
+    ) -> Option<Vec<NextHop<'x>>>;
+}
+
+impl ToNextHop for RecordSet<MX> {
+    fn to_remote_hosts<'x, 'y: 'x>(
+        &'x self,
+        domain: &'y str,
+        config: &'x MxConfig,
+    ) -> Option<Vec<NextHop<'x>>> {
+        if !self.rrset.is_empty() {
+            // Obtain max number of MX hosts to process
+            let mut remote_hosts = Vec::with_capacity(config.max_mx);
+
+            'outer: for mx in self.rrset.iter() {
+                if mx.exchanges.len() > 1 {
+                    let mut slice = mx.exchanges.iter().collect::<Vec<_>>();
+                    slice.shuffle(&mut rand::rng());
+                    for remote_host in slice {
+                        remote_hosts.push(NextHop::MX {
+                            host: remote_host.as_ref(),
+                            is_implicit: false,
+                            dnssec_status: self.dnssec_status,
+                            config,
+                        });
+                        if remote_hosts.len() == config.max_mx {
+                            break 'outer;
+                        }
+                    }
+                } else if let Some(remote_host) = mx.exchanges.first() {
+                    // Check for Null MX
+                    if mx.preference == 0 && remote_host.as_ref() == "." {
+                        return None;
+                    }
+                    remote_hosts.push(NextHop::MX {
+                        host: remote_host.as_ref(),
+                        is_implicit: false,
+                        dnssec_status: self.dnssec_status,
+                        config,
+                    });
+                    if remote_hosts.len() == config.max_mx {
+                        break;
+                    }
+                }
+            }
+            remote_hosts.into()
+        } else {
+            // If an empty list of MXs is returned, the address is treated as if it was
+            // associated with an implicit MX RR with a preference of 0, pointing to that host.
+            vec![NextHop::MX {
+                host: domain,
+                is_implicit: true,
+                dnssec_status: self.dnssec_status,
+                config,
+            }]
+            .into()
+        }
+    }
+}

crates/smtp/src/outbound/mod.rs

@@ -0,0 +1,379 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use crate::{
+    outbound::{client::BoxResponse, error::ClientError},
+    queue::{Error, ErrorDetails, HostResponse, Status, UnexpectedResponse},
+};
+use common::config::{
+    server::ServerProtocol,
+    smtp::queue::{HostOrIp, MxConfig, RelayConfig},
+};
+use directory::Credentials;
+use mail_auth::{DnssecStatus, IpLookupStrategy};
+use smtp_proto::{Response, Severity};
+use std::{borrow::Cow, net::IpAddr};
+
+pub mod client;
+pub mod dane;
+pub mod delivery;
+pub mod error;
+pub mod local;
+pub mod lookup;
+pub mod mta_sts;
+pub mod session;
+
+pub(super) enum DeliveryResult {
+    Domain {
+        status: Status<HostResponse<Box<str>>, ErrorDetails>,
+        rcpt_idxs: Vec<usize>,
+    },
+    Account {
+        status: Status<HostResponse<Box<str>>, ErrorDetails>,
+        rcpt_idx: usize,
+    },
+    RateLimited {
+        rcpt_idxs: Vec<usize>,
+        retry_at: u64,
+    },
+}
+
+impl Status<HostResponse<Box<str>>, ErrorDetails> {
+    pub fn from_smtp_error(hostname: &str, command: &str, err: ClientError) -> Self {
+        match err {
+            ClientError::Io(_)
+            | ClientError::Tls(_)
+            | ClientError::Base64(_)
+            | ClientError::UnparseableReply
+            | ClientError::AuthenticationFailed(_)
+            | ClientError::MissingCredentials
+            | ClientError::MissingMailFrom
+            | ClientError::MissingRcptTo
+            | ClientError::Timeout => Status::TemporaryFailure(ErrorDetails {
+                entity: hostname.into(),
+                details: Error::ConnectionError(err.to_string().into_boxed_str()),
+            }),
+
+            ClientError::UnexpectedReply(response) => {
+                if response.severity() == Severity::PermanentNegativeCompletion {
+                    Status::PermanentFailure(ErrorDetails {
+                        entity: hostname.into(),
+                        details: Error::UnexpectedResponse(UnexpectedResponse {
+                            command: command.trim().into(),
+                            response: response.into_box(),
+                        }),
+                    })
+                } else {
+                    Status::TemporaryFailure(ErrorDetails {
+                        entity: hostname.into(),
+                        details: Error::UnexpectedResponse(UnexpectedResponse {
+                            command: command.trim().into(),
+                            response: response.into_box(),
+                        }),
+                    })
+                }
+            }
+
+            ClientError::InvalidChallenge
+            | ClientError::UnsupportedAuthMechanism
+            | ClientError::InvalidTLSName
+            | ClientError::MissingStartTls => Status::PermanentFailure(ErrorDetails {
+                entity: hostname.into(),
+                details: Error::ConnectionError(err.to_string().into_boxed_str()),
+            }),
+        }
+    }
+
+    pub fn from_starttls_error(hostname: &str, response: Option<Response<Box<str>>>) -> Self {
+        let entity = hostname.into();
+        if let Some(response) = response {
+            if response.severity() == Severity::PermanentNegativeCompletion {
+                Status::PermanentFailure(ErrorDetails {
+                    entity,
+                    details: Error::UnexpectedResponse(UnexpectedResponse {
+                        command: "STARTTLS".into(),
+                        response,
+                    }),
+                })
+            } else {
+                Status::TemporaryFailure(ErrorDetails {
+                    entity,
+                    details: Error::UnexpectedResponse(UnexpectedResponse {
+                        command: "STARTTLS".into(),
+                        response,
+                    }),
+                })
+            }
+        } else {
+            Status::PermanentFailure(ErrorDetails {
+                entity,
+                details: Error::TlsError("STARTTLS not advertised by host.".into()),
+            })
+        }
+    }
+
+    pub fn from_tls_error(hostname: &str, err: ClientError) -> Self {
+        match err {
+            ClientError::InvalidTLSName => Status::PermanentFailure(ErrorDetails {
+                entity: hostname.into(),
+                details: Error::TlsError("Invalid hostname".into()),
+            }),
+            ClientError::Timeout => Status::TemporaryFailure(ErrorDetails {
+                entity: hostname.into(),
+                details: Error::TlsError("TLS handshake timed out".into()),
+            }),
+            ClientError::Tls(err) => Status::TemporaryFailure(ErrorDetails {
+                entity: hostname.into(),
+                details: Error::TlsError(format!("Handshake failed: {err}").into_boxed_str()),
+            }),
+            ClientError::Io(err) => Status::TemporaryFailure(ErrorDetails {
+                entity: hostname.into(),
+                details: Error::TlsError(format!("I/O error: {err}").into_boxed_str()),
+            }),
+            _ => Status::PermanentFailure(ErrorDetails {
+                entity: hostname.into(),
+                details: Error::TlsError("Other TLS error".into()),
+            }),
+        }
+    }
+
+    pub fn timeout(hostname: &str, stage: &str) -> Self {
+        Status::TemporaryFailure(ErrorDetails {
+            entity: hostname.into(),
+            details: Error::ConnectionError(format!("Timeout while {stage}").into_boxed_str()),
+        })
+    }
+
+    pub fn local_error() -> Self {
+        Status::TemporaryFailure(ErrorDetails {
+            entity: "localhost".into(),
+            details: Error::ConnectionError("Could not deliver message locally.".into()),
+        })
+    }
+
+    pub fn from_mail_auth_error(entity: &str, err: mail_auth::Error) -> Self {
+        match &err {
+            mail_auth::Error::Dns(mail_auth::DnsError::RecordNotFound(code)) => {
+                Status::PermanentFailure(ErrorDetails {
+                    entity: entity.into(),
+                    details: Error::DnsError(
+                        format!("Domain not found: {code:?}").into_boxed_str(),
+                    ),
+                })
+            }
+            _ => Status::TemporaryFailure(ErrorDetails {
+                entity: entity.into(),
+                details: Error::DnsError(err.to_string().into_boxed_str()),
+            }),
+        }
+    }
+
+    pub fn from_mta_sts_error(entity: &str, err: mta_sts::Error) -> Self {
+        match &err {
+            mta_sts::Error::Dns(err) => match err {
+                mail_auth::Error::Dns(mail_auth::DnsError::RecordNotFound(code)) => {
+                    Status::PermanentFailure(ErrorDetails {
+                        entity: entity.into(),
+                        details: Error::MtaStsError(
+                            format!("Record not found: {code:?}").into_boxed_str(),
+                        ),
+                    })
+                }
+                mail_auth::Error::Dns(mail_auth::DnsError::InvalidRecordType) => {
+                    Status::PermanentFailure(ErrorDetails {
+                        entity: entity.into(),
+                        details: Error::MtaStsError("Failed to parse MTA-STS DNS record.".into()),
+                    })
+                }
+                _ => Status::TemporaryFailure(ErrorDetails {
+                    entity: entity.into(),
+                    details: Error::MtaStsError(
+                        format!("DNS lookup error: {err}").into_boxed_str(),
+                    ),
+                }),
+            },
+            mta_sts::Error::Http(err) => {
+                if err.is_timeout() {
+                    Status::TemporaryFailure(ErrorDetails {
+                        entity: entity.into(),
+                        details: Error::MtaStsError("Timeout fetching policy.".into()),
+                    })
+                } else if err.is_connect() {
+                    Status::TemporaryFailure(ErrorDetails {
+                        entity: entity.into(),
+                        details: Error::MtaStsError("Could not reach policy host.".into()),
+                    })
+                } else if err.is_status()
+                    & err
+                        .status()
+                        .is_some_and(|s| s == reqwest::StatusCode::NOT_FOUND)
+                {
+                    Status::PermanentFailure(ErrorDetails {
+                        entity: entity.into(),
+                        details: Error::MtaStsError("Policy not found.".into()),
+                    })
+                } else {
+                    Status::TemporaryFailure(ErrorDetails {
+                        entity: entity.into(),
+                        details: Error::MtaStsError("Failed to fetch policy.".into()),
+                    })
+                }
+            }
+            mta_sts::Error::InvalidPolicy(err) => Status::PermanentFailure(ErrorDetails {
+                entity: entity.into(),
+                details: Error::MtaStsError(
+                    format!("Failed to parse policy: {err}").into_boxed_str(),
+                ),
+            }),
+        }
+    }
+}
+
+#[derive(Debug)]
+pub enum NextHop<'x> {
+    Relay(&'x RelayConfig),
+    MX {
+        is_implicit: bool,
+        host: &'x str,
+        config: &'x MxConfig,
+        dnssec_status: DnssecStatus,
+    },
+}
+
+impl NextHop<'_> {
+    #[inline(always)]
+    pub fn hostname(&self) -> &str {
+        match self {
+            NextHop::MX { host, .. } => {
+                if let Some(host) = host.strip_suffix('.') {
+                    host
+                } else {
+                    host
+                }
+            }
+            NextHop::Relay(host) => match &host.address {
+                HostOrIp::Host(host) => host.as_ref(),
+                HostOrIp::Ip(ip) => ip.ip_str.as_ref(),
+            },
+        }
+    }
+
+    #[inline(always)]
+    pub fn fqdn_hostname(&self) -> HostOrIp<Cow<'_, str>, IpAddr> {
+        match self {
+            NextHop::MX { host, .. } => {
+                if !host.ends_with('.') {
+                    HostOrIp::Host(format!("{host}.").into())
+                } else {
+                    HostOrIp::Host((*host).into())
+                }
+            }
+            NextHop::Relay(host) => match &host.address {
+                HostOrIp::Host(host) => HostOrIp::Host(host.as_ref().into()),
+                HostOrIp::Ip(ip) => HostOrIp::Ip(ip.ip),
+            },
+        }
+    }
+
+    #[inline(always)]
+    pub fn max_multi_homed(&self) -> usize {
+        match self {
+            NextHop::MX { config, .. } => config.max_multi_homed,
+            NextHop::Relay(_) => 10,
+        }
+    }
+
+    #[inline(always)]
+    pub fn ip_lookup_strategy(&self) -> IpLookupStrategy {
+        match self {
+            NextHop::MX { config, .. } => config.ip_lookup_strategy,
+            NextHop::Relay(_) => IpLookupStrategy::Ipv4thenIpv6,
+        }
+    }
+
+    #[inline(always)]
+    fn port(&self) -> u16 {
+        match self {
+            #[cfg(feature = "test_mode")]
+            NextHop::MX { .. } => 9925,
+            #[cfg(not(feature = "test_mode"))]
+            NextHop::MX { .. } => 25,
+            NextHop::Relay(host) => host.port,
+        }
+    }
+
+    #[inline(always)]
+    fn allow_loopback(&self) -> bool {
+        match self {
+            NextHop::MX { .. } => cfg!(feature = "test_mode"),
+            NextHop::Relay(_) => true,
+        }
+    }
+
+    #[inline(always)]
+    fn credentials(&self) -> Option<&Credentials> {
+        match self {
+            NextHop::MX { .. } => None,
+            NextHop::Relay(host) => host.auth.as_ref(),
+        }
+    }
+
+    #[inline(always)]
+    fn allow_invalid_certs(&self) -> bool {
+        #[cfg(feature = "test_mode")]
+        {
+            true
+        }
+        #[cfg(not(feature = "test_mode"))]
+        match self {
+            NextHop::MX { .. } => false,
+            NextHop::Relay(host) => host.tls_allow_invalid_certs,
+        }
+    }
+
+    #[inline(always)]
+    fn implicit_tls(&self) -> bool {
+        match self {
+            NextHop::MX { .. } => false,
+            NextHop::Relay(host) => host.tls_implicit,
+        }
+    }
+
+    #[inline(always)]
+    fn is_smtp(&self) -> bool {
+        match self {
+            NextHop::MX { .. } => true,
+            NextHop::Relay(host) => host.protocol == ServerProtocol::Smtp,
+        }
+    }
+
+    fn dnssec_status(&self) -> DnssecStatus {
+        match self {
+            NextHop::MX { dnssec_status, .. } => *dnssec_status,
+            NextHop::Relay(_) => DnssecStatus::Indeterminate,
+        }
+    }
+}
+
+impl DeliveryResult {
+    pub fn domain(
+        status: Status<HostResponse<Box<str>>, ErrorDetails>,
+        rcpt_idxs: Vec<usize>,
+    ) -> Self {
+        DeliveryResult::Domain { status, rcpt_idxs }
+    }
+
+    pub fn rate_limited(rcpt_idxs: Vec<usize>, retry_at: u64) -> Self {
+        DeliveryResult::RateLimited {
+            rcpt_idxs,
+            retry_at,
+        }
+    }
+
+    pub fn account(status: Status<HostResponse<Box<str>>, ErrorDetails>, rcpt_idx: usize) -> Self {
+        DeliveryResult::Account { status, rcpt_idx }
+    }
+}

crates/smtp/src/outbound/mta_sts/lookup.rs

@@ -0,0 +1,158 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use std::{fmt::Display, sync::Arc, time::Duration};
+
+#[cfg(feature = "test_mode")]
+pub static STS_TEST_POLICY: parking_lot::Mutex<Vec<u8>> = parking_lot::Mutex::new(Vec::new());
+
+use common::{Server, config::smtp::resolver::Policy};
+use mail_auth::{mta_sts::MtaSts, report::tlsrpt::ResultType};
+
+use super::{Error, parse::ParsePolicy};
+
+#[cfg(not(feature = "test_mode"))]
+use utils::HttpLimitResponse;
+
+#[cfg(not(feature = "test_mode"))]
+const MAX_POLICY_SIZE: usize = 1024 * 1024;
+
+pub trait MtaStsLookup: Sync + Send {
+    fn lookup_mta_sts_policy(
+        &self,
+        domain: &str,
+        timeout: Duration,
+    ) -> impl std::future::Future<Output = Result<Arc<Policy>, Error>> + Send;
+}
+
+#[allow(unused_variables)]
+impl MtaStsLookup for Server {
+    async fn lookup_mta_sts_policy(
+        &self,
+        domain: &str,
+        timeout: Duration,
+    ) -> Result<Arc<Policy>, Error> {
+        // Lookup MTA-STS TXT record
+        let record = match self
+            .core
+            .smtp
+            .resolvers
+            .dns
+            .txt_lookup::<MtaSts>(
+                format!("_mta-sts.{domain}."),
+                Some(&self.inner.cache.dns_txt),
+            )
+            .await
+        {
+            Ok(record) => record,
+            Err(err) => {
+                // Return the cached policy in case of failure
+                return if let Some(value) = self.inner.cache.dns_mta_sts.get(domain) {
+                    Ok(value)
+                } else {
+                    Err(err.into())
+                };
+            }
+        };
+
+        // Check if the policy has been cached
+        if let Some(value) = self.inner.cache.dns_mta_sts.get(domain)
+            && value.id == record.id
+        {
+            return Ok(value);
+        }
+
+        // Fetch policy
+        #[cfg(not(feature = "test_mode"))]
+        let bytes = self
+            .core
+            .smtp
+            .mta_sts_client
+            .get(format!("https://mta-sts.{domain}/.well-known/mta-sts.txt"))
+            .timeout(timeout)
+            .send()
+            .await?
+            .bytes_with_limit(MAX_POLICY_SIZE)
+            .await?
+            .ok_or_else(|| Error::InvalidPolicy("Policy too large".to_string()))?;
+        #[cfg(feature = "test_mode")]
+        let bytes = STS_TEST_POLICY.lock().clone();
+
+        // Parse policy
+        let policy = Arc::new(Policy::parse(
+            std::str::from_utf8(&bytes).map_err(|err| Error::InvalidPolicy(err.to_string()))?,
+            record.id.clone(),
+        )?);
+
+        self.inner.cache.dns_mta_sts.insert(
+            domain.into(),
+            policy.clone(),
+            Duration::from_secs(if (3600..31557600).contains(&policy.max_age) {
+                policy.max_age
+            } else {
+                86400
+            }),
+        );
+
+        Ok(policy)
+    }
+}
+
+impl From<&Error> for ResultType {
+    fn from(err: &Error) -> Self {
+        match &err {
+            Error::InvalidPolicy(_) => ResultType::StsPolicyInvalid,
+            _ => ResultType::StsPolicyFetchError,
+        }
+    }
+}
+
+impl Display for Error {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Error::Dns(err) => match err {
+                mail_auth::Error::Dns(mail_auth::DnsError::RecordNotFound(code)) => {
+                    write!(f, "Record not found: {code:?}")
+                }
+                mail_auth::Error::Dns(mail_auth::DnsError::InvalidRecordType) => {
+                    f.write_str("Failed to parse MTA-STS DNS record.")
+                }
+                _ => write!(f, "DNS lookup error: {err}"),
+            },
+            Error::Http(err) => {
+                if err.is_timeout() {
+                    f.write_str("Timeout fetching policy.")
+                } else if err.is_connect() {
+                    f.write_str("Could not reach policy host.")
+                } else if err.is_status() && (err.status() == Some(reqwest::StatusCode::NOT_FOUND))
+                {
+                    f.write_str("Policy not found.")
+                } else {
+                    f.write_str("Failed to fetch policy.")
+                }
+            }
+            Error::InvalidPolicy(err) => write!(f, "Failed to parse policy: {err}"),
+        }
+    }
+}
+
+impl From<mail_auth::Error> for Error {
+    fn from(value: mail_auth::Error) -> Self {
+        Error::Dns(value)
+    }
+}
+
+impl From<reqwest::Error> for Error {
+    fn from(value: reqwest::Error) -> Self {
+        Error::Http(value)
+    }
+}
+
+impl From<String> for Error {
+    fn from(value: String) -> Self {
+        Error::InvalidPolicy(value)
+    }
+}

crates/smtp/src/outbound/mta_sts/mod.rs

@@ -0,0 +1,16 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+pub mod lookup;
+pub mod parse;
+pub mod verify;
+
+#[derive(Debug)]
+pub enum Error {
+    Dns(mail_auth::Error),
+    Http(reqwest::Error),
+    InvalidPolicy(String),
+}

crates/smtp/src/outbound/mta_sts/parse.rs

@@ -0,0 +1,110 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use common::config::smtp::resolver::{Mode, MxPattern, Policy};
+use utils::DomainPart;
+
+fn to_a_label(domain: &str) -> String {
+    domain
+        .to_ascii_domain()
+        .map(|domain| domain.to_lowercase())
+        .unwrap_or_else(|| domain.to_lowercase())
+}
+
+pub trait ParsePolicy {
+    fn parse(data: &str, id: String) -> Result<Self, String>
+    where
+        Self: Sized;
+}
+
+impl ParsePolicy for Policy {
+    fn parse(mut data: &str, id: String) -> Result<Policy, String> {
+        let mut mode = Mode::None;
+        let mut max_age: u64 = 86400;
+        let mut mx = Vec::new();
+
+        while !data.is_empty() {
+            if let Some((key, next_data)) = data.split_once(':') {
+                let value = if let Some((value, next_data)) = next_data.split_once('\n') {
+                    data = next_data;
+                    value.trim()
+                } else {
+                    data = "";
+                    next_data.trim()
+                };
+                hashify::fnc_map!(key.trim().as_bytes(),
+                    b"mx" => {
+                        if let Some(suffix) = value.strip_prefix("*.") {
+                            if !suffix.is_empty() {
+                                mx.push(MxPattern::StartsWith(to_a_label(suffix)));
+                            }
+                        } else if !value.is_empty() {
+                            mx.push(MxPattern::Equals(to_a_label(value)));
+                        }
+                    },
+                    b"max_age" => {
+                        if let Ok(value) = value.parse() {
+                            max_age = value;
+                        }
+                    },
+                    b"mode" => {
+                        mode = match value {
+                            "enforce" => Mode::Enforce,
+                            "testing" => Mode::Testing,
+                            "none" => Mode::None,
+                            _ => return Err(format!("Unsupported mode {value:?}.")),
+                        };
+                    },
+                    b"version" => {
+                        if !value.eq_ignore_ascii_case("STSv1") {
+                            return Err(format!("Unsupported version {value:?}."));
+                        }
+                    },
+                    _ => {}
+                );
+            } else {
+                break;
+            }
+        }
+
+        if !mx.is_empty() {
+            Ok(Policy {
+                id,
+                mode,
+                mx: mx.into_boxed_slice(),
+                max_age,
+            })
+        } else {
+            Err("No 'mx' entries found.".to_string())
+        }
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::ParsePolicy;
+    use crate::outbound::mta_sts::verify::VerifyPolicy;
+    use common::config::smtp::resolver::Policy;
+
+    #[test]
+    fn mx_patterns_are_a_labels() {
+        let policy = Policy::parse(
+            concat!(
+                "version: STSv1\n",
+                "mode: enforce\n",
+                "mx: *.\u{5de}\u{5d9}\u{5d9}\u{5dc}.\u{5e7}\u{5d5}\u{5dd}\n",
+                "mx: MAIL.\u{5de}\u{5d9}\u{5d9}\u{5dc}.\u{5e7}\u{5d5}\u{5dd}\n",
+                "max_age: 604800\n"
+            ),
+            "test".to_string(),
+        )
+        .unwrap();
+
+        assert!(policy.verify("mx.xn--eebajf.xn--9dbq2a"));
+        assert!(policy.verify("mail.xn--eebajf.xn--9dbq2a"));
+        assert!(!policy.verify("mx.example.org"));
+    }
+}

crates/smtp/src/outbound/mta_sts/verify.rs

@@ -0,0 +1,43 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use common::config::smtp::resolver::{Mode, MxPattern, Policy};
+
+pub trait VerifyPolicy {
+    fn verify(&self, mx_host: &str) -> bool;
+    fn enforce(&self) -> bool;
+}
+
+impl VerifyPolicy for Policy {
+    fn verify(&self, mx_host: &str) -> bool {
+        if self.mode != Mode::None {
+            for mx_pattern in &self.mx {
+                match mx_pattern {
+                    MxPattern::Equals(host) => {
+                        if host == mx_host {
+                            return true;
+                        }
+                    }
+                    MxPattern::StartsWith(domain) => {
+                        if let Some((_, suffix)) = mx_host.split_once('.')
+                            && suffix == domain
+                        {
+                            return true;
+                        }
+                    }
+                }
+            }
+
+            false
+        } else {
+            true
+        }
+    }
+
+    fn enforce(&self) -> bool {
+        self.mode == Mode::Enforce
+    }
+}

crates/smtp/src/outbound/session.rs

@@ -0,0 +1,481 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use super::client::SmtpClient;
+use crate::outbound::DeliveryResult;
+use crate::outbound::client::{BoxResponse, from_error_status, from_mail_send_error};
+use crate::outbound::error::ClientError;
+use crate::queue::{Error, MessageWrapper, Recipient, Status};
+use crate::queue::{ErrorDetails, HostResponse, UnexpectedResponse};
+use common::Server;
+use common::config::smtp::queue::ConnectionStrategy;
+use directory::Credentials;
+use smtp_proto::{
+    EXT_CHUNKING, EXT_DSN, EXT_REQUIRE_TLS, EXT_SIZE, EXT_SMTP_UTF8, EhloResponse, MAIL_REQUIRETLS,
+    MAIL_RET_FULL, MAIL_RET_HDRS, MAIL_SMTPUTF8, RCPT_NOTIFY_DELAY, RCPT_NOTIFY_FAILURE,
+    RCPT_NOTIFY_NEVER, RCPT_NOTIFY_SUCCESS, Severity,
+};
+use std::{fmt::Write, time::Instant};
+use tokio::io::{AsyncRead, AsyncWrite};
+use trc::DeliveryEvent;
+
+pub struct SessionParams<'x> {
+    pub server: &'x Server,
+    pub hostname: &'x str,
+    pub credentials: Option<&'x Credentials>,
+    pub capabilities: Option<EhloResponse<String>>,
+    pub is_smtp: bool,
+    pub local_hostname: &'x str,
+    pub conn_strategy: &'x ConnectionStrategy,
+    pub session_id: u64,
+}
+
+impl MessageWrapper {
+    pub(super) async fn deliver<T: AsyncRead + AsyncWrite + Unpin>(
+        &self,
+        mut smtp_client: SmtpClient<T>,
+        rcpt_idxs: Vec<usize>,
+        rcpt_headers: Option<&[u8]>,
+        statuses: &mut Vec<DeliveryResult>,
+        mut params: SessionParams<'_>,
+    ) {
+        // Obtain capabilities
+        let time = Instant::now();
+        let capabilities = if let Some(capabilities) = params.capabilities.take() {
+            capabilities
+        } else {
+            match smtp_client.say_helo(&params).await {
+                Ok(capabilities) => {
+                    trc::event!(
+                        Delivery(DeliveryEvent::Ehlo),
+                        SpanId = params.session_id,
+                        Hostname = params.hostname.to_string(),
+                        Details = capabilities.capabilities(),
+                        Elapsed = time.elapsed(),
+                    );
+
+                    capabilities
+                }
+                Err(status) => {
+                    trc::event!(
+                        Delivery(DeliveryEvent::EhloRejected),
+                        SpanId = params.session_id,
+                        Hostname = params.hostname.to_string(),
+                        CausedBy = from_error_status(&status),
+                        Elapsed = time.elapsed(),
+                    );
+                    smtp_client.quit().await;
+                    statuses.push(DeliveryResult::domain(status, rcpt_idxs));
+                    return;
+                }
+            }
+        };
+
+        // Authenticate
+        if let Some(credentials) = params.credentials {
+            let time = Instant::now();
+            if let Err(err) = smtp_client.authenticate(credentials, &capabilities).await {
+                trc::event!(
+                    Delivery(DeliveryEvent::AuthFailed),
+                    SpanId = params.session_id,
+                    Hostname = params.hostname.to_string(),
+                    CausedBy = from_mail_send_error(&err),
+                    Elapsed = time.elapsed(),
+                );
+
+                smtp_client.quit().await;
+                statuses.push(DeliveryResult::domain(
+                    Status::from_smtp_error(params.hostname, "AUTH ...", err),
+                    rcpt_idxs,
+                ));
+                return;
+            }
+
+            trc::event!(
+                Delivery(DeliveryEvent::Auth),
+                SpanId = params.session_id,
+                Hostname = params.hostname.to_string(),
+                Elapsed = time.elapsed(),
+            );
+
+            // Refresh capabilities
+            // Disabled as some SMTP servers deauthenticate after EHLO
+            /*capabilities = match say_helo(&mut smtp_client, &params).await {
+                Ok(capabilities) => capabilities,
+                Err(status) => {
+                    trc::event!(
+
+                        context = "ehlo",
+                        event = "rejected",
+                        mx = &params.hostname,
+                        reason = %status,
+                    );
+                    smtp_client.quit().await;
+                    return status;
+                }
+            };*/
+        }
+
+        // MAIL FROM
+        let time = Instant::now();
+        smtp_client.timeout = params.conn_strategy.timeout_mail;
+        let cmd = self.build_mail_from(&capabilities);
+        match smtp_client.cmd(cmd.as_bytes()).await.and_then(|r| {
+            if r.is_positive_completion() {
+                Ok(r)
+            } else {
+                Err(ClientError::UnexpectedReply(Box::new(r)))
+            }
+        }) {
+            Ok(response) => {
+                trc::event!(
+                    Delivery(DeliveryEvent::MailFrom),
+                    SpanId = params.session_id,
+                    Hostname = params.hostname.to_string(),
+                    From = self.message.return_path.to_string(),
+                    Code = response.code,
+                    Details = response.message.to_string(),
+                    Elapsed = time.elapsed(),
+                );
+            }
+            Err(err) => {
+                trc::event!(
+                    Delivery(DeliveryEvent::MailFromRejected),
+                    SpanId = params.session_id,
+                    Hostname = params.hostname.to_string(),
+                    CausedBy = from_mail_send_error(&err),
+                    Elapsed = time.elapsed(),
+                );
+
+                smtp_client.quit().await;
+                statuses.push(DeliveryResult::domain(
+                    Status::from_smtp_error(params.hostname, &cmd, err),
+                    rcpt_idxs,
+                ));
+                return;
+            }
+        }
+
+        // RCPT TO
+        let mut accepted_rcpts = Vec::new();
+        smtp_client.timeout = params.conn_strategy.timeout_rcpt;
+        for rcpt_idx in &rcpt_idxs {
+            let time = Instant::now();
+            let rcpt = &self.message.recipients[*rcpt_idx];
+            if matches!(
+                &rcpt.status,
+                Status::Completed(_) | Status::PermanentFailure(_)
+            ) {
+                continue;
+            }
+
+            let cmd = self.build_rcpt_to(rcpt, &capabilities);
+            match smtp_client.cmd(cmd.as_bytes()).await {
+                Ok(response) => match response.severity() {
+                    Severity::PositiveCompletion => {
+                        trc::event!(
+                            Delivery(DeliveryEvent::RcptTo),
+                            SpanId = params.session_id,
+                            Hostname = params.hostname.to_string(),
+                            To = rcpt.address().to_string(),
+                            Code = response.code,
+                            Details = response.message.to_string(),
+                            Elapsed = time.elapsed(),
+                        );
+
+                        accepted_rcpts.push((
+                            rcpt,
+                            rcpt_idx,
+                            Status::Completed(HostResponse {
+                                hostname: params.hostname.into(),
+                                response: response.into_box(),
+                            }),
+                        ));
+                    }
+                    severity => {
+                        trc::event!(
+                            Delivery(DeliveryEvent::RcptToRejected),
+                            SpanId = params.session_id,
+                            Hostname = params.hostname.to_string(),
+                            To = rcpt.address().to_string(),
+                            Code = response.code,
+                            Details = response.message.to_string(),
+                            Elapsed = time.elapsed(),
+                        );
+
+                        let response = ErrorDetails {
+                            entity: params.hostname.into(),
+                            details: Error::UnexpectedResponse(UnexpectedResponse {
+                                command: cmd.trim().into(),
+                                response: response.into_box(),
+                            }),
+                        };
+                        statuses.push(DeliveryResult::account(
+                            if severity == Severity::PermanentNegativeCompletion {
+                                Status::PermanentFailure(response)
+                            } else {
+                                Status::TemporaryFailure(response)
+                            },
+                            *rcpt_idx,
+                        ));
+                    }
+                },
+                Err(err) => {
+                    trc::event!(
+                        Delivery(DeliveryEvent::RcptToFailed),
+                        SpanId = params.session_id,
+                        Hostname = params.hostname.to_string(),
+                        To = rcpt.address().to_string(),
+                        CausedBy = from_mail_send_error(&err),
+                        Elapsed = time.elapsed(),
+                    );
+
+                    // Something went wrong, abort.
+                    smtp_client.quit().await;
+                    statuses.push(DeliveryResult::domain(
+                        Status::from_smtp_error(params.hostname, "", err),
+                        rcpt_idxs,
+                    ));
+                    return;
+                }
+            }
+        }
+
+        // Send message
+        if !accepted_rcpts.is_empty() {
+            let time = Instant::now();
+            let mut bdat_cmd = capabilities.has_capability(EXT_CHUNKING).then(String::new);
+
+            if let Err(status) = smtp_client
+                .send_message(self, rcpt_headers, &mut bdat_cmd, &params)
+                .await
+            {
+                trc::event!(
+                    Delivery(DeliveryEvent::MessageRejected),
+                    SpanId = params.session_id,
+                    Hostname = params.hostname.to_string(),
+                    CausedBy = from_error_status(&status),
+                    Elapsed = time.elapsed(),
+                );
+
+                smtp_client.quit().await;
+                statuses.push(DeliveryResult::domain(status, rcpt_idxs));
+                return;
+            }
+
+            if params.is_smtp {
+                // Handle SMTP response
+                match smtp_client
+                    .read_smtp_data_response(params.hostname, &bdat_cmd)
+                    .await
+                {
+                    Ok(response) => {
+                        // Mark recipients as delivered
+                        if response.code() == 250 {
+                            for (rcpt, rcpt_idx, status) in accepted_rcpts {
+                                trc::event!(
+                                    Delivery(DeliveryEvent::Delivered),
+                                    SpanId = params.session_id,
+                                    Hostname = params.hostname.to_string(),
+                                    To = rcpt.address().to_string(),
+                                    Code = response.code,
+                                    Details = response.message.to_string(),
+                                    Elapsed = time.elapsed(),
+                                );
+
+                                statuses.push(DeliveryResult::account(status, *rcpt_idx));
+                            }
+                        } else {
+                            trc::event!(
+                                Delivery(DeliveryEvent::MessageRejected),
+                                SpanId = params.session_id,
+                                Hostname = params.hostname.to_string(),
+                                Code = response.code,
+                                Details = response.message.to_string(),
+                                Elapsed = time.elapsed(),
+                            );
+
+                            smtp_client.quit().await;
+                            statuses.push(DeliveryResult::domain(
+                                Status::from_smtp_error(
+                                    params.hostname,
+                                    bdat_cmd.as_deref().unwrap_or("DATA"),
+                                    ClientError::UnexpectedReply(Box::new(response)),
+                                ),
+                                rcpt_idxs,
+                            ));
+                            return;
+                        }
+                    }
+                    Err(status) => {
+                        trc::event!(
+                            Delivery(DeliveryEvent::MessageRejected),
+                            SpanId = params.session_id,
+                            Hostname = params.hostname.to_string(),
+                            CausedBy = from_error_status(&status),
+                            Elapsed = time.elapsed(),
+                        );
+
+                        smtp_client.quit().await;
+                        statuses.push(DeliveryResult::domain(status, rcpt_idxs));
+                        return;
+                    }
+                }
+            } else {
+                // Handle LMTP responses
+                match smtp_client
+                    .read_lmtp_data_response(params.hostname, accepted_rcpts.len())
+                    .await
+                {
+                    Ok(responses) => {
+                        for ((rcpt, rcpt_idx, _), response) in
+                            accepted_rcpts.into_iter().zip(responses)
+                        {
+                            let status: Status<HostResponse<Box<str>>, ErrorDetails> =
+                                match response.severity() {
+                                    Severity::PositiveCompletion => {
+                                        trc::event!(
+                                            Delivery(DeliveryEvent::Delivered),
+                                            SpanId = params.session_id,
+                                            Hostname = params.hostname.to_string(),
+                                            To = rcpt.address().to_string(),
+                                            Code = response.code,
+                                            Details = response.message.to_string(),
+                                            Elapsed = time.elapsed(),
+                                        );
+
+                                        Status::Completed(HostResponse {
+                                            hostname: params.hostname.into(),
+                                            response,
+                                        })
+                                    }
+                                    severity => {
+                                        trc::event!(
+                                            Delivery(DeliveryEvent::RcptToRejected),
+                                            SpanId = params.session_id,
+                                            Hostname = params.hostname.to_string(),
+                                            To = rcpt.address().to_string(),
+                                            Code = response.code,
+                                            Details = response.message.to_string(),
+                                            Elapsed = time.elapsed(),
+                                        );
+
+                                        let response = ErrorDetails {
+                                            entity: params.hostname.into(),
+                                            details: Error::UnexpectedResponse(
+                                                UnexpectedResponse {
+                                                    command: bdat_cmd
+                                                        .as_deref()
+                                                        .unwrap_or("DATA")
+                                                        .into(),
+                                                    response,
+                                                },
+                                            ),
+                                        };
+                                        if severity == Severity::PermanentNegativeCompletion {
+                                            Status::PermanentFailure(response)
+                                        } else {
+                                            Status::TemporaryFailure(response)
+                                        }
+                                    }
+                                };
+
+                            statuses.push(DeliveryResult::account(status, *rcpt_idx));
+                        }
+                    }
+                    Err(status) => {
+                        trc::event!(
+                            Delivery(DeliveryEvent::MessageRejected),
+                            SpanId = params.session_id,
+                            Hostname = params.hostname.to_string(),
+                            CausedBy = from_error_status(&status),
+                            Elapsed = time.elapsed(),
+                        );
+
+                        smtp_client.quit().await;
+                        statuses.push(DeliveryResult::domain(status, rcpt_idxs));
+                        return;
+                    }
+                }
+            }
+        }
+
+        smtp_client.quit().await;
+    }
+
+    fn build_mail_from(&self, capabilities: &EhloResponse<String>) -> String {
+        let mut mail_from = String::with_capacity(self.message.return_path.len() + 60);
+        let _ = write!(mail_from, "MAIL FROM:<{}>", self.message.return_path);
+        if capabilities.has_capability(EXT_SIZE) {
+            let _ = write!(mail_from, " SIZE={}", self.message.size);
+        }
+        if self.has_flag(MAIL_REQUIRETLS) & capabilities.has_capability(EXT_REQUIRE_TLS) {
+            mail_from.push_str(" REQUIRETLS");
+        }
+        if self.has_flag(MAIL_SMTPUTF8) & capabilities.has_capability(EXT_SMTP_UTF8) {
+            mail_from.push_str(" SMTPUTF8");
+        }
+        if capabilities.has_capability(EXT_DSN) {
+            if self.has_flag(MAIL_RET_FULL) {
+                mail_from.push_str(" RET=FULL");
+            } else if self.has_flag(MAIL_RET_HDRS) {
+                mail_from.push_str(" RET=HDRS");
+            }
+            if let Some(env_id) = &self.message.env_id {
+                let _ = write!(mail_from, " ENVID={env_id}");
+            }
+        }
+
+        mail_from.push_str("\r\n");
+        mail_from
+    }
+
+    fn build_rcpt_to(&self, rcpt: &Recipient, capabilities: &EhloResponse<String>) -> String {
+        let mut rcpt_to = String::with_capacity(rcpt.address().len() + 60);
+        let _ = write!(rcpt_to, "RCPT TO:<{}>", rcpt.address());
+        if capabilities.has_capability(EXT_DSN) {
+            if rcpt.has_flag(RCPT_NOTIFY_SUCCESS | RCPT_NOTIFY_FAILURE | RCPT_NOTIFY_DELAY) {
+                rcpt_to.push_str(" NOTIFY=");
+                let mut add_comma = if rcpt.has_flag(RCPT_NOTIFY_SUCCESS) {
+                    rcpt_to.push_str("SUCCESS");
+                    true
+                } else {
+                    false
+                };
+                if rcpt.has_flag(RCPT_NOTIFY_DELAY) {
+                    if add_comma {
+                        rcpt_to.push(',');
+                    } else {
+                        add_comma = true;
+                    }
+                    rcpt_to.push_str("DELAY");
+                }
+                if rcpt.has_flag(RCPT_NOTIFY_FAILURE) {
+                    if add_comma {
+                        rcpt_to.push(',');
+                    }
+                    rcpt_to.push_str("FAILURE");
+                }
+            } else if rcpt.has_flag(RCPT_NOTIFY_NEVER) {
+                rcpt_to.push_str(" NOTIFY=NEVER");
+            }
+        }
+        rcpt_to.push_str("\r\n");
+        rcpt_to
+    }
+
+    #[inline(always)]
+    pub fn has_flag(&self, flag: u64) -> bool {
+        (self.message.flags & flag) != 0
+    }
+}
+
+impl Recipient {
+    #[inline(always)]
+    pub fn has_flag(&self, flag: u64) -> bool {
+        (self.flags & flag) != 0
+    }
+}

crates/smtp/src/queue/dsn.rs

@@ -0,0 +1,669 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use super::spool::SmtpSpool;
+use super::{
+    Error, ErrorDetails, HostResponse, Message, MessageSource, QueueEnvelope, RCPT_DSN_SENT,
+    Recipient, Status,
+};
+use crate::inbound::dkim::DkimSign;
+use crate::queue::spool::QueueParams;
+use crate::queue::{MessageWrapper, UnexpectedResponse};
+use common::Server;
+use mail_builder::MessageBuilder;
+use mail_builder::headers::HeaderType;
+use mail_builder::headers::content_type::ContentType;
+use mail_builder::mime::{BodyPart, MimePart, make_boundary};
+use mail_parser::DateTime;
+use smtp_proto::{
+    RCPT_NOTIFY_DELAY, RCPT_NOTIFY_FAILURE, RCPT_NOTIFY_NEVER, RCPT_NOTIFY_SUCCESS, Response,
+};
+use std::fmt::Write;
+use std::future::Future;
+use store::write::now;
+
+pub trait SendDsn: Sync + Send {
+    fn send_dsn(&self, message: &mut MessageWrapper) -> impl Future<Output = ()> + Send;
+    fn log_dsn(&self, message: &MessageWrapper) -> impl Future<Output = ()> + Send;
+}
+
+impl SendDsn for Server {
+    async fn send_dsn(&self, message: &mut MessageWrapper) {
+        // Send DSN events
+        self.log_dsn(message).await;
+
+        if !message.message.return_path.is_empty() {
+            // Build DSN
+            if let Some(dsn) = message.build_dsn(self).await {
+                let mut dsn_message = self.new_message("", MessageSource::Dsn, message.span_id);
+                dsn_message
+                    .expand_and_add_recipient(message.message.return_path.as_ref(), self)
+                    .await;
+
+                // Queue DSN
+                let dkim_signers = self
+                    .eval_signers(
+                        &self.core.smtp.queue.dsn.sign,
+                        &message.message,
+                        message.span_id,
+                    )
+                    .await;
+                dsn_message
+                    .queue(
+                        QueueParams::new(&dsn, message.span_id, self)
+                            .with_dkim_signers(dkim_signers),
+                    )
+                    .await;
+            }
+        } else {
+            // Handle double bounce
+            message.handle_double_bounce();
+        }
+
+        // Update next DSN notify times
+        message.update_next_dsn(self).await;
+    }
+
+    async fn log_dsn(&self, message: &MessageWrapper) {
+        let now = now();
+
+        for rcpt in &message.message.recipients {
+            if rcpt.has_flag(RCPT_DSN_SENT) {
+                continue;
+            }
+
+            match &rcpt.status {
+                Status::Completed(response) => {
+                    trc::event!(
+                        Delivery(trc::DeliveryEvent::DsnSuccess),
+                        SpanId = message.span_id,
+                        To = rcpt.address.clone(),
+                        Hostname = response.hostname.clone(),
+                        Code = response.response.code,
+                        Details = response.response.message.to_string(),
+                    );
+                }
+                Status::TemporaryFailure(response) if rcpt.notify.due <= now => {
+                    trc::event!(
+                        Delivery(trc::DeliveryEvent::DsnTempFail),
+                        SpanId = message.span_id,
+                        To = rcpt.address.clone(),
+                        Hostname = response.entity.clone(),
+                        Details = response.details.to_string(),
+                        NextRetry = trc::Value::Timestamp(rcpt.retry.due),
+                        Expires = rcpt
+                            .expiration_time(message.message.created)
+                            .map(trc::Value::Timestamp),
+                        Total = rcpt.retry.inner,
+                    );
+                }
+                Status::PermanentFailure(response) => {
+                    trc::event!(
+                        Delivery(trc::DeliveryEvent::DsnPermFail),
+                        SpanId = message.span_id,
+                        To = rcpt.address.clone(),
+                        Hostname = response.entity.clone(),
+                        Details = response.details.to_string(),
+                        Total = rcpt.retry.inner,
+                    );
+                }
+                Status::Scheduled if rcpt.notify.due <= now => {
+                    trc::event!(
+                        Delivery(trc::DeliveryEvent::DsnTempFail),
+                        SpanId = message.span_id,
+                        To = rcpt.address.clone(),
+                        Details = "Concurrency limited",
+                        NextRetry = trc::Value::Timestamp(rcpt.retry.due),
+                        Expires = rcpt
+                            .expiration_time(message.message.created)
+                            .map(trc::Value::Timestamp),
+                        Total = rcpt.retry.inner,
+                    );
+                }
+                _ => continue,
+            }
+        }
+    }
+}
+
+const MAX_HEADER_SIZE: usize = 4096;
+
+impl MessageWrapper {
+    pub async fn build_dsn(&mut self, server: &Server) -> Option<Vec<u8>> {
+        let config = &server.core.smtp.queue;
+        let now = now();
+
+        let mut txt_success = String::new();
+        let mut txt_delay = String::new();
+        let mut txt_failed = String::new();
+        let mut dsn = String::new();
+
+        for rcpt in &mut self.message.recipients {
+            if rcpt.has_flag(RCPT_DSN_SENT | RCPT_NOTIFY_NEVER) {
+                continue;
+            }
+            match &rcpt.status {
+                Status::Completed(response) => {
+                    rcpt.flags |= RCPT_DSN_SENT;
+                    if !rcpt.has_flag(RCPT_NOTIFY_SUCCESS) {
+                        continue;
+                    }
+                    rcpt.write_dsn(&mut dsn);
+                    rcpt.status.write_dsn(&mut dsn);
+                    response.write_dsn_text(&rcpt.address, &mut txt_success);
+                }
+                Status::TemporaryFailure(response)
+                    if rcpt.notify.due <= now && rcpt.has_flag(RCPT_NOTIFY_DELAY) =>
+                {
+                    rcpt.write_dsn(&mut dsn);
+                    rcpt.status.write_dsn(&mut dsn);
+                    rcpt.write_dsn_will_retry_until(self.message.created, &mut dsn);
+                    response.write_dsn_text(&rcpt.address, &mut txt_delay);
+                }
+                Status::PermanentFailure(response) => {
+                    rcpt.flags |= RCPT_DSN_SENT;
+                    if !rcpt.has_flag(RCPT_NOTIFY_FAILURE) {
+                        continue;
+                    }
+                    rcpt.write_dsn(&mut dsn);
+                    rcpt.status.write_dsn(&mut dsn);
+                    response.write_dsn_text(&rcpt.address, &mut txt_failed);
+                }
+                Status::Scheduled if rcpt.notify.due <= now && rcpt.has_flag(RCPT_NOTIFY_DELAY) => {
+                    // This case should not happen under normal circumstances
+                    rcpt.write_dsn(&mut dsn);
+                    rcpt.status.write_dsn(&mut dsn);
+                    rcpt.write_dsn_will_retry_until(self.message.created, &mut dsn);
+                    ErrorDetails {
+                        entity: "localhost".into(),
+                        details: Error::ConcurrencyLimited,
+                    }
+                    .write_dsn_text(&rcpt.address, &mut txt_delay);
+                }
+                _ => continue,
+            }
+
+            dsn.push_str("\r\n");
+        }
+
+        let txt_len = txt_success.len() + txt_delay.len() + txt_failed.len();
+        if txt_len == 0 {
+            return None;
+        }
+
+        let has_success = !txt_success.is_empty();
+        let has_delay = !txt_delay.is_empty();
+        let has_failure = !txt_failed.is_empty();
+
+        let mut txt = String::with_capacity(txt_len + 128);
+        let (subject, is_mixed) = if has_success && !has_delay && !has_failure {
+            txt.push_str(
+                "Your message has been successfully delivered to the following recipients:\r\n\r\n",
+            );
+            ("Successfully delivered message", false)
+        } else if has_delay && !has_success && !has_failure {
+            txt.push_str("There was a temporary problem delivering your message to the following recipients:\r\n\r\n");
+            ("Warning: Delay in message delivery", false)
+        } else if has_failure && !has_success && !has_delay {
+            txt.push_str(
+                "Your message could not be delivered to the following recipients:\r\n\r\n",
+            );
+            ("Failed to deliver message", false)
+        } else if has_success {
+            txt.push_str("Your message has been partially delivered:\r\n\r\n");
+            ("Partially delivered message", true)
+        } else {
+            txt.push_str("Your message could not be delivered to some recipients:\r\n\r\n");
+            (
+                "Warning: Temporary and permanent failures during message delivery",
+                true,
+            )
+        };
+
+        if has_success {
+            if is_mixed {
+                txt.push_str(
+                    "    ----- Delivery to the following addresses was successful -----\r\n",
+                );
+            }
+
+            txt.push_str(&txt_success);
+            txt.push_str("\r\n");
+        }
+
+        if has_delay {
+            if is_mixed {
+                txt.push_str(
+                    "    ----- There was a temporary problem delivering to these addresses -----\r\n",
+                );
+            }
+            txt.push_str(&txt_delay);
+            txt.push_str("\r\n");
+        }
+
+        if has_failure {
+            if is_mixed {
+                txt.push_str("    ----- Delivery to the following addresses failed -----\r\n");
+            }
+            txt.push_str(&txt_failed);
+            txt.push_str("\r\n");
+        }
+
+        // Obtain hostname and sender addresses
+        let from_name = server
+            .eval_if(&config.dsn.name, &self.message, self.span_id)
+            .await
+            .unwrap_or_else(|| String::from("Mail Delivery Subsystem"));
+        let from_addr = server
+            .eval_if(&config.dsn.address, &self.message, self.span_id)
+            .await
+            .unwrap_or_else(|| String::from("MAILER-DAEMON@localhost"));
+        let reporting_mta = server
+            .eval_if(
+                &server.core.smtp.report.submitter,
+                &self.message,
+                self.span_id,
+            )
+            .await
+            .unwrap_or_else(|| String::from("localhost"));
+
+        // Prepare DSN
+        let mut dsn_header = String::with_capacity(dsn.len() + 128);
+        self.message
+            .write_dsn_headers(&mut dsn_header, &reporting_mta);
+        let dsn = dsn_header + dsn.as_str();
+
+        // Fetch up to MAX_HEADER_SIZE bytes of message headers
+        let headers = match server
+            .blob_store()
+            .get_blob(self.message.blob_hash.as_slice(), 0..MAX_HEADER_SIZE)
+            .await
+        {
+            Ok(Some(mut buf)) => {
+                let mut prev_ch = 0;
+                let mut last_lf = buf.len();
+                for (pos, &ch) in buf.iter().enumerate() {
+                    match ch {
+                        b'\n' => {
+                            last_lf = pos + 1;
+                            if prev_ch != b'\n' {
+                                prev_ch = ch;
+                            } else {
+                                break;
+                            }
+                        }
+                        b'\r' => (),
+                        0 => break,
+                        _ => {
+                            prev_ch = ch;
+                        }
+                    }
+                }
+                if last_lf < MAX_HEADER_SIZE {
+                    buf.truncate(last_lf);
+                }
+                String::from_utf8(buf).unwrap_or_default()
+            }
+            Ok(None) => {
+                trc::event!(
+                    Queue(trc::QueueEvent::BlobNotFound),
+                    SpanId = self.span_id,
+                    BlobId = self.message.blob_hash.to_hex(),
+                    CausedBy = trc::location!()
+                );
+
+                String::new()
+            }
+            Err(err) => {
+                trc::error!(
+                    err.span_id(self.span_id)
+                        .details("Failed to fetch blobId")
+                        .caused_by(trc::location!())
+                );
+
+                String::new()
+            }
+        };
+
+        // Build message
+        MessageBuilder::new()
+            .from((from_name.as_str(), from_addr.as_str()))
+            .header(
+                "To",
+                HeaderType::Text(self.message.return_path.as_ref().into()),
+            )
+            .header("Auto-Submitted", HeaderType::Text("auto-generated".into()))
+            .message_id(format!("{}@{}", make_boundary("."), reporting_mta))
+            .subject(subject)
+            .body(MimePart::new(
+                ContentType::new("multipart/report").attribute("report-type", "delivery-status"),
+                BodyPart::Multipart(vec![
+                    MimePart::new(ContentType::new("text/plain"), BodyPart::Text(txt.into())),
+                    MimePart::new(
+                        ContentType::new("message/delivery-status"),
+                        BodyPart::Text(dsn.into()),
+                    ),
+                    MimePart::new(
+                        ContentType::new("message/rfc822"),
+                        BodyPart::Text(headers.into()),
+                    ),
+                ]),
+            ))
+            .write_to_vec()
+            .unwrap_or_default()
+            .into()
+    }
+
+    pub async fn update_next_dsn(&mut self, server: &Server) {
+        let now = now();
+        let mut notify_changes = Vec::new();
+        for (rcpt_idx, rcpt) in self.message.recipients.iter().enumerate() {
+            if matches!(
+                &rcpt.status,
+                Status::TemporaryFailure(_) | Status::Scheduled
+            ) && rcpt.notify.due <= now
+            {
+                let envelope = QueueEnvelope::new(&self.message, rcpt);
+
+                let queue_id = server
+                    .eval_if::<String, _>(&server.core.smtp.queue.queue, &envelope, self.span_id)
+                    .await
+                    .unwrap_or_else(|| "default".to_string());
+                let queue = server.get_queue_or_default(&queue_id, self.span_id);
+
+                if let Some(next_notify) =
+                    queue.notify.get((rcpt.notify.inner + 1) as usize).copied()
+                {
+                    notify_changes.push((rcpt_idx, 1, now + next_notify));
+                } else {
+                    notify_changes.push((rcpt_idx, 0, u64::MAX));
+                }
+            }
+        }
+
+        for (rcpt_idx, inner, due) in notify_changes {
+            let rcpt = &mut self.message.recipients[rcpt_idx];
+            rcpt.notify.inner += inner;
+            rcpt.notify.due = due;
+        }
+    }
+
+    fn handle_double_bounce(&mut self) {
+        let mut is_double_bounce = Vec::with_capacity(0);
+        let now = now();
+
+        for rcpt in &mut self.message.recipients {
+            if !rcpt.has_flag(RCPT_DSN_SENT | RCPT_NOTIFY_NEVER)
+                && let Status::PermanentFailure(err) = &rcpt.status
+            {
+                rcpt.flags |= RCPT_DSN_SENT;
+                let mut dsn = String::new();
+                err.write_dsn_text(&rcpt.address, &mut dsn);
+                is_double_bounce.push(dsn);
+            }
+
+            if rcpt.notify.due <= now {
+                rcpt.notify.due = rcpt
+                    .expiration_time(self.message.created)
+                    .map(|d| d + 10)
+                    .unwrap_or(u64::MAX);
+            }
+        }
+
+        if !is_double_bounce.is_empty() {
+            trc::event!(
+                Delivery(trc::DeliveryEvent::DoubleBounce),
+                SpanId = self.span_id,
+                To = is_double_bounce
+            );
+        }
+    }
+}
+
+impl HostResponse<Box<str>> {
+    fn write_dsn_text(&self, addr: &str, dsn: &mut String) {
+        let _ = write!(
+            dsn,
+            "<{}> (delivered to '{}' with code {} ({}.{}.{}) '",
+            addr,
+            self.hostname,
+            self.response.code,
+            self.response.esc[0],
+            self.response.esc[1],
+            self.response.esc[2]
+        );
+        self.response.write_response(dsn);
+        dsn.push_str("')\r\n");
+    }
+}
+
+impl UnexpectedResponse {
+    fn write_dsn_text(&self, host: &str, addr: &str, dsn: &mut String) {
+        let _ = write!(dsn, "<{addr}> (host '{host}' rejected ");
+
+        if !self.command.is_empty() {
+            let _ = write!(dsn, "command '{}'", self.command);
+        } else {
+            dsn.push_str("transaction");
+        }
+
+        let _ = write!(
+            dsn,
+            " with code {} ({}.{}.{}) '",
+            self.response.code, self.response.esc[0], self.response.esc[1], self.response.esc[2]
+        );
+        self.response.write_response(dsn);
+        dsn.push_str("')\r\n");
+    }
+}
+
+impl ErrorDetails {
+    fn write_dsn_text(&self, addr: &str, dsn: &mut String) {
+        let entity = self.entity.as_ref();
+        match &self.details {
+            Error::UnexpectedResponse(response) => {
+                response.write_dsn_text(entity, addr, dsn);
+            }
+            Error::DnsError(err) => {
+                let _ = write!(dsn, "<{addr}> (failed to lookup '{entity}': {err})\r\n",);
+            }
+            Error::ConnectionError(details) => {
+                let _ = write!(
+                    dsn,
+                    "<{addr}> (connection to '{entity}' failed: {details})\r\n",
+                );
+            }
+            Error::TlsError(details) => {
+                let _ = write!(dsn, "<{addr}> (TLS error from '{entity}': {details})\r\n",);
+            }
+            Error::DaneError(details) => {
+                let _ = write!(
+                    dsn,
+                    "<{addr}> (DANE failed to authenticate '{entity}': {details})\r\n",
+                );
+            }
+            Error::MtaStsError(details) => {
+                let _ = write!(
+                    dsn,
+                    "<{addr}> (MTA-STS failed to authenticate '{entity}': {details})\r\n",
+                );
+            }
+            Error::RateLimited => {
+                let _ = write!(dsn, "<{addr}> (rate limited)\r\n");
+            }
+            Error::ConcurrencyLimited => {
+                let _ = write!(
+                    dsn,
+                    "<{addr}> (too many concurrent connections to remote server)\r\n",
+                );
+            }
+            Error::Io(err) => {
+                let _ = write!(dsn, "<{addr}> (queue error: {err})\r\n");
+            }
+        }
+    }
+}
+
+impl Message {
+    fn write_dsn_headers(&self, dsn: &mut String, reporting_mta: &str) {
+        let _ = write!(dsn, "Reporting-MTA: dns;{reporting_mta}\r\n");
+        dsn.push_str("Arrival-Date: ");
+        dsn.push_str(&DateTime::from_timestamp(self.created as i64).to_rfc822());
+        dsn.push_str("\r\n");
+        if let Some(env_id) = &self.env_id {
+            let _ = write!(dsn, "Original-Envelope-Id: {env_id}\r\n");
+        }
+        dsn.push_str("\r\n");
+    }
+}
+
+impl Recipient {
+    fn write_dsn(&self, dsn: &mut String) {
+        if let Some(orcpt) = &self.orcpt {
+            let _ = write!(dsn, "Original-Recipient: rfc822;{orcpt}\r\n");
+        }
+        let _ = write!(dsn, "Final-Recipient: rfc822;{}\r\n", self.address);
+    }
+
+    fn write_dsn_will_retry_until(&self, created: u64, dsn: &mut String) {
+        if let Some(expires) = self.expiration_time(created)
+            && expires > now()
+        {
+            dsn.push_str("Will-Retry-Until: ");
+            dsn.push_str(&DateTime::from_timestamp(expires as i64).to_rfc822());
+            dsn.push_str("\r\n");
+        }
+    }
+}
+
+impl<T, E> Status<T, E> {
+    pub fn into_permanent(self) -> Self {
+        match self {
+            Status::TemporaryFailure(v) => Status::PermanentFailure(v),
+            v => v,
+        }
+    }
+
+    pub fn into_temporary(self) -> Self {
+        match self {
+            Status::PermanentFailure(err) => Status::TemporaryFailure(err),
+            other => other,
+        }
+    }
+
+    pub fn is_permanent(&self) -> bool {
+        matches!(self, Status::PermanentFailure(_))
+    }
+
+    fn write_dsn_action(&self, dsn: &mut String) {
+        dsn.push_str("Action: ");
+        dsn.push_str(match self {
+            Status::Completed(_) => "delivered",
+            Status::PermanentFailure(_) => "failed",
+            Status::TemporaryFailure(_) | Status::Scheduled => "delayed",
+        });
+        dsn.push_str("\r\n");
+    }
+}
+
+impl Status<HostResponse<Box<str>>, ErrorDetails> {
+    fn write_dsn(&self, dsn: &mut String) {
+        self.write_dsn_action(dsn);
+        self.write_dsn_status(dsn);
+        self.write_dsn_diagnostic(dsn);
+        self.write_dsn_remote_mta(dsn);
+    }
+
+    fn write_dsn_status(&self, dsn: &mut String) {
+        dsn.push_str("Status: ");
+        match self {
+            Status::Completed(response) => {
+                response.response.write_dsn_status(dsn);
+            }
+            Status::TemporaryFailure(err) | Status::PermanentFailure(err) => {
+                if let Error::UnexpectedResponse(response) = &err.details {
+                    response.response.write_dsn_status(dsn);
+                } else {
+                    dsn.push_str(if matches!(self, Status::PermanentFailure(_)) {
+                        "5.0.0"
+                    } else {
+                        "4.0.0"
+                    });
+                }
+            }
+            Status::Scheduled => {
+                dsn.push_str("4.0.0");
+            }
+        }
+        dsn.push_str("\r\n");
+    }
+
+    fn write_dsn_remote_mta(&self, dsn: &mut String) {
+        match self {
+            Status::Completed(response) => {
+                dsn.push_str("Remote-MTA: dns;");
+                dsn.push_str(&response.hostname);
+                dsn.push_str("\r\n");
+            }
+            Status::TemporaryFailure(err) | Status::PermanentFailure(err) => match &err.details {
+                Error::UnexpectedResponse(_)
+                | Error::ConnectionError(_)
+                | Error::TlsError(_)
+                | Error::DaneError(_) => {
+                    dsn.push_str("Remote-MTA: dns;");
+                    dsn.push_str(&err.entity);
+                    dsn.push_str("\r\n");
+                }
+                _ => (),
+            },
+            Status::Scheduled => (),
+        }
+    }
+
+    fn write_dsn_diagnostic(&self, dsn: &mut String) {
+        if let Status::PermanentFailure(err) | Status::TemporaryFailure(err) = self
+            && let Error::UnexpectedResponse(response) = &err.details
+        {
+            response.response.write_dsn_diagnostic(dsn);
+        }
+    }
+}
+
+impl WriteDsn for Response<Box<str>> {
+    fn write_dsn_status(&self, dsn: &mut String) {
+        if self.esc[0] > 0 {
+            let _ = write!(dsn, "{}.{}.{}", self.esc[0], self.esc[1], self.esc[2]);
+        } else {
+            let _ = write!(
+                dsn,
+                "{}.{}.{}",
+                self.code / 100,
+                (self.code / 10) % 10,
+                self.code % 10
+            );
+        }
+    }
+
+    fn write_dsn_diagnostic(&self, dsn: &mut String) {
+        let _ = write!(dsn, "Diagnostic-Code: smtp;{} ", self.code);
+        self.write_response(dsn);
+        dsn.push_str("\r\n");
+    }
+
+    fn write_response(&self, dsn: &mut String) {
+        for ch in self.message.chars() {
+            if ch != '\n' && ch != '\r' {
+                dsn.push(ch);
+            }
+        }
+    }
+}
+
+trait WriteDsn {
+    fn write_dsn_status(&self, dsn: &mut String);
+    fn write_dsn_diagnostic(&self, dsn: &mut String);
+    fn write_response(&self, dsn: &mut String);
+}

crates/smtp/src/queue/manager.rs

@@ -0,0 +1,501 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use super::{Message, QueueId, Status, spool::SmtpSpool};
+use crate::queue::{
+    Recipient,
+    spool::{INFINITE_LOCK, LOCK_EXPIRY, QUEUE_REFRESH},
+};
+use ahash::AHashMap;
+use common::{
+    BuildServer, Inner,
+    config::smtp::queue::{QueueExpiry, QueueName},
+    ipc::{QueueEvent, QueueEventStatus},
+};
+use rand::{RngExt, seq::SliceRandom};
+use std::{
+    collections::hash_map::Entry,
+    sync::{Arc, atomic::Ordering},
+    time::{Duration, Instant},
+};
+use store::write::now;
+use tokio::sync::mpsc;
+
+pub struct Queue {
+    pub core: Arc<Inner>,
+    pub locked: AHashMap<(QueueId, QueueName), LockedMessage>,
+    pub locked_revision: u64,
+    pub stats: AHashMap<QueueName, QueueStats>,
+    pub next_refresh: Instant,
+    pub rx: mpsc::Receiver<QueueEvent>,
+    pub is_paused: bool,
+    pub scan_from: u64,
+    pub scan_ceiling: u64,
+    pub has_pending_work: bool,
+    pub pending_refresh: bool,
+    pub urgent_refresh: bool,
+    pub last_scan: Instant,
+    pub last_full_scan: Instant,
+}
+
+#[derive(Debug)]
+pub struct QueueStats {
+    pub in_flight: usize,
+    pub max_in_flight: usize,
+    pub budget: usize,
+    pub last_warning: Instant,
+}
+
+#[derive(Debug)]
+pub struct LockedMessage {
+    pub expires: u64,
+    pub revision: u64,
+    pub due: u64,
+}
+
+impl SpawnQueue for mpsc::Receiver<QueueEvent> {
+    fn spawn(self, core: Arc<Inner>) {
+        tokio::spawn(async move {
+            Queue::new(core, self).start().await;
+        });
+    }
+}
+
+const BACK_PRESSURE_WARN_INTERVAL: Duration = Duration::from_secs(60);
+const MIN_SCAN_INTERVAL: Duration = Duration::from_millis(100);
+const FULL_SCAN_INTERVAL: Duration = Duration::from_secs(QUEUE_REFRESH / 2);
+
+impl Queue {
+    pub fn new(core: Arc<Inner>, rx: mpsc::Receiver<QueueEvent>) -> Self {
+        let now = Instant::now();
+
+        Queue {
+            core,
+            locked: AHashMap::with_capacity(128),
+            locked_revision: 0,
+            stats: AHashMap::new(),
+            next_refresh: now + Duration::from_secs(1),
+            is_paused: false,
+            rx,
+            scan_from: 0,
+            scan_ceiling: u64::MAX,
+            has_pending_work: false,
+            pending_refresh: false,
+            urgent_refresh: false,
+            last_scan: now.checked_sub(MIN_SCAN_INTERVAL).unwrap_or(now),
+            last_full_scan: now,
+        }
+    }
+
+    pub async fn start(&mut self) {
+        trc::event!(Queue(trc::QueueEvent::Started));
+
+        loop {
+            let mut refresh_queue;
+
+            match tokio::time::timeout(
+                self.next_refresh.duration_since(Instant::now()),
+                self.rx.recv(),
+            )
+            .await
+            {
+                Ok(Some(event)) => {
+                    refresh_queue = self.handle_event(event).await;
+
+                    while let Ok(event) = self.rx.try_recv() {
+                        refresh_queue = self.handle_event(event).await || refresh_queue;
+                    }
+                }
+                Err(_) => {
+                    refresh_queue = true;
+                    self.urgent_refresh = true;
+                }
+                Ok(None) => {
+                    break;
+                }
+            };
+
+            if self.is_paused {
+                self.next_refresh = Instant::now() + Duration::from_secs(86400);
+                continue;
+            }
+
+            self.pending_refresh |= refresh_queue;
+            if !self.pending_refresh && self.next_refresh > Instant::now() {
+                continue;
+            }
+
+            // Coalesce bursts of worker notifications into a single scan
+            let scan_at = self.last_scan + MIN_SCAN_INTERVAL;
+            if !self.urgent_refresh && scan_at > Instant::now() {
+                self.next_refresh = scan_at;
+                continue;
+            }
+
+            if self.scan_from != 0 && self.last_full_scan.elapsed() >= FULL_SCAN_INTERVAL {
+                self.scan_from = 0;
+            }
+            if self.scan_from == 0 {
+                self.last_full_scan = Instant::now();
+            }
+            let scan_floor = self.scan_from;
+            self.pending_refresh = false;
+            self.urgent_refresh = false;
+
+            // Process queue events
+            let server = self.core.build_server();
+            let mut queue_events = server.next_event(self).await;
+            self.last_scan = Instant::now();
+
+            if queue_events.messages.len() > 3 {
+                queue_events.messages.shuffle(&mut rand::rng());
+            }
+
+            // A truncated scan left events behind
+            let now = now();
+            self.has_pending_work = self.scan_ceiling != u64::MAX;
+
+            for queue_event in &queue_events.messages {
+                // A message may hold more than one event key, dispatch it only once
+                if self
+                    .locked
+                    .get(&(queue_event.queue_id, queue_event.queue_name))
+                    .is_some_and(|locked| locked.expires > now)
+                {
+                    continue;
+                }
+
+                // Fetch queue stats
+                let stats = match self.stats.get_mut(&queue_event.queue_name) {
+                    Some(stats) => stats,
+                    None => {
+                        let queue_config =
+                            server.get_virtual_queue_or_default(&queue_event.queue_name);
+                        self.stats.insert(
+                            queue_event.queue_name,
+                            QueueStats::new(queue_config.threads),
+                        );
+                        self.stats.get_mut(&queue_event.queue_name).unwrap()
+                    }
+                };
+
+                // Enforce concurrency limits
+                if stats.has_capacity() {
+                    // Deliver message
+                    stats.in_flight += 1;
+                    self.locked.insert(
+                        (queue_event.queue_id, queue_event.queue_name),
+                        LockedMessage {
+                            expires: now + INFINITE_LOCK,
+                            revision: self.locked_revision,
+                            due: queue_event.due,
+                        },
+                    );
+                    queue_event.try_deliver(server.clone());
+                } else {
+                    if stats.last_warning.elapsed() >= BACK_PRESSURE_WARN_INTERVAL {
+                        stats.last_warning = Instant::now();
+                        trc::event!(
+                            Queue(trc::QueueEvent::BackPressure),
+                            Reason = "Processing capacity for this queue exceeded.",
+                            QueueName = queue_event.queue_name.to_string(),
+                            Limit = stats.max_in_flight,
+                        );
+                    }
+                    self.has_pending_work = true;
+                    if queue_event.due < self.scan_from {
+                        self.scan_from = queue_event.due;
+                    }
+                }
+            }
+
+            // Remove expired locks, revisiting any event they were holding back
+            let scan_ceiling = self.scan_ceiling;
+            let mut dropped_due = u64::MAX;
+            self.locked.retain(|_, locked| {
+                let keep = locked.expires > now
+                    && (locked.revision == self.locked_revision
+                        || locked.due < scan_floor
+                        || locked.due >= scan_ceiling);
+                if !keep && locked.due < dropped_due {
+                    dropped_due = locked.due;
+                }
+                keep
+            });
+
+            // Do not wait for the next scheduled event while there is work left over
+            let mut next_refresh = queue_events.next_refresh.saturating_sub(now);
+            if self.has_pending_work {
+                next_refresh = std::cmp::min(next_refresh, FULL_SCAN_INTERVAL.as_secs());
+            }
+            let mut next_refresh = Instant::now() + Duration::from_secs(next_refresh);
+
+            // A released lock uncovered an event below the floor that no scan can see
+            if dropped_due < self.scan_from {
+                self.scan_from = dropped_due;
+                self.has_pending_work = true;
+                self.pending_refresh = true;
+
+                let scan_at = self.last_scan + MIN_SCAN_INTERVAL;
+                if scan_at < next_refresh {
+                    next_refresh = scan_at;
+                }
+            }
+
+            self.next_refresh = next_refresh;
+        }
+    }
+
+    async fn handle_event(&mut self, event: QueueEvent) -> bool {
+        match event {
+            QueueEvent::WorkerDone {
+                queue_id,
+                queue_name,
+                status,
+            } => {
+                let has_capacity = match self.stats.get_mut(&queue_name) {
+                    Some(queue_stats) => {
+                        queue_stats.in_flight = queue_stats.in_flight.saturating_sub(1);
+                        queue_stats.has_capacity()
+                    }
+                    None => true,
+                };
+
+                match status {
+                    QueueEventStatus::Completed => {
+                        self.core.ipc.task_tx.notify_one();
+                        self.locked.remove(&(queue_id, queue_name));
+                        !self.locked.is_empty() || !has_capacity || self.has_pending_work
+                    }
+                    QueueEventStatus::Locked => {
+                        let expires = LOCK_EXPIRY + rand::rng().random_range(5..10);
+                        let due_in = Instant::now() + Duration::from_secs(expires);
+                        if due_in < self.next_refresh {
+                            self.next_refresh = due_in;
+                        }
+
+                        // The event was not delivered, so it has to be visited again
+                        // once the remote lock expires.
+                        let expires = now() + expires;
+                        let due = match self.locked.entry((queue_id, queue_name)) {
+                            Entry::Occupied(mut entry) => {
+                                let locked = entry.get_mut();
+                                locked.expires = expires;
+                                locked.revision = self.locked_revision;
+                                locked.due
+                            }
+                            Entry::Vacant(entry) => {
+                                entry.insert(LockedMessage {
+                                    expires,
+                                    revision: self.locked_revision,
+                                    due: 0,
+                                });
+                                0
+                            }
+                        };
+                        if due < self.scan_from {
+                            self.scan_from = due;
+                        }
+                        self.locked.len() > 1 || !has_capacity || self.has_pending_work
+                    }
+                    QueueEventStatus::Deferred => {
+                        self.locked.remove(&(queue_id, queue_name));
+                        self.scan_from = 0;
+                        true
+                    }
+                }
+            }
+            QueueEvent::Refresh => {
+                self.scan_from = 0;
+                self.urgent_refresh = true;
+                true
+            }
+            QueueEvent::Paused(paused) => {
+                self.core
+                    .data
+                    .queue_status
+                    .store(!paused, Ordering::Relaxed);
+                self.is_paused = paused;
+                self.scan_from = 0;
+                self.urgent_refresh = !paused;
+                !paused
+            }
+            QueueEvent::ReloadSettings => {
+                let server = self.core.build_server();
+                let virtual_queues = &server.core.smtp.queue.virtual_queues;
+                for (name, settings) in virtual_queues {
+                    if let Some(stats) = self.stats.get_mut(name) {
+                        stats.max_in_flight = settings.threads;
+                    } else {
+                        self.stats.insert(*name, QueueStats::new(settings.threads));
+                    }
+                }
+                self.stats
+                    .retain(|name, stats| stats.in_flight > 0 || virtual_queues.contains_key(name));
+                self.scan_from = 0;
+                false
+            }
+            QueueEvent::Stop => {
+                self.rx.close();
+                self.is_paused = true;
+                false
+            }
+        }
+    }
+}
+
+impl Message {
+    pub fn next_event(&self, queue: Option<QueueName>) -> Option<u64> {
+        let mut next_event = None;
+
+        for rcpt in &self.recipients {
+            if matches!(rcpt.status, Status::Scheduled | Status::TemporaryFailure(_))
+                && queue.is_none_or(|q| rcpt.queue == q)
+            {
+                let mut earlier_event = std::cmp::min(rcpt.retry.due, rcpt.notify.due);
+
+                if let Some(expires) = rcpt.expiration_time(self.created) {
+                    earlier_event = std::cmp::min(earlier_event, expires);
+                }
+
+                if let Some(next_event) = &mut next_event {
+                    if earlier_event < *next_event {
+                        *next_event = earlier_event;
+                    }
+                } else {
+                    next_event = Some(earlier_event);
+                }
+            }
+        }
+
+        next_event
+    }
+
+    pub fn next_delivery_event(&self, queue: Option<QueueName>) -> Option<u64> {
+        let mut next_delivery = None;
+
+        for rcpt in self.recipients.iter().filter(|rcpt| {
+            matches!(rcpt.status, Status::Scheduled | Status::TemporaryFailure(_))
+                && queue.is_none_or(|q| rcpt.queue == q)
+        }) {
+            if let Some(next_delivery) = &mut next_delivery {
+                if rcpt.retry.due < *next_delivery {
+                    *next_delivery = rcpt.retry.due;
+                }
+            } else {
+                next_delivery = Some(rcpt.retry.due);
+            }
+        }
+
+        next_delivery
+    }
+
+    pub fn next_dsn(&self, queue: Option<QueueName>) -> Option<u64> {
+        let mut next_dsn = None;
+
+        for rcpt in self.recipients.iter().filter(|rcpt| {
+            matches!(rcpt.status, Status::Scheduled | Status::TemporaryFailure(_))
+                && queue.is_none_or(|q| rcpt.queue == q)
+        }) {
+            if let Some(next_dsn) = &mut next_dsn {
+                if rcpt.notify.due < *next_dsn {
+                    *next_dsn = rcpt.notify.due;
+                }
+            } else {
+                next_dsn = Some(rcpt.notify.due);
+            }
+        }
+
+        next_dsn
+    }
+
+    pub fn expires(&self, queue: Option<QueueName>) -> Option<u64> {
+        let mut expires = None;
+
+        for rcpt in self.recipients.iter().filter(|d| {
+            matches!(d.status, Status::Scheduled | Status::TemporaryFailure(_))
+                && queue.is_none_or(|q| d.queue == q)
+        }) {
+            if let Some(rcpt_expires) = rcpt.expiration_time(self.created) {
+                if let Some(expires) = &mut expires {
+                    if rcpt_expires > *expires {
+                        *expires = rcpt_expires;
+                    }
+                } else {
+                    expires = Some(rcpt_expires)
+                }
+            }
+        }
+
+        expires
+    }
+
+    pub fn next_events(&self) -> AHashMap<QueueName, u64> {
+        let mut next_events = AHashMap::new();
+
+        for rcpt in &self.recipients {
+            if matches!(rcpt.status, Status::Scheduled | Status::TemporaryFailure(_)) {
+                let mut earlier_event = std::cmp::min(rcpt.retry.due, rcpt.notify.due);
+
+                if let Some(expires) = rcpt.expiration_time(self.created) {
+                    earlier_event = std::cmp::min(earlier_event, expires);
+                }
+
+                match next_events.entry(rcpt.queue) {
+                    Entry::Occupied(mut entry) => {
+                        let entry = entry.get_mut();
+                        if earlier_event < *entry {
+                            *entry = earlier_event;
+                        }
+                    }
+                    Entry::Vacant(entry) => {
+                        entry.insert(earlier_event);
+                    }
+                }
+            }
+        }
+
+        next_events
+    }
+}
+
+impl Recipient {
+    pub fn expiration_time(&self, created: u64) -> Option<u64> {
+        match self.expires {
+            QueueExpiry::Ttl(time) => Some(created + time),
+            QueueExpiry::Attempts(_) => None,
+        }
+    }
+
+    pub fn is_expired(&self, created: u64, now: u64) -> bool {
+        match self.expires {
+            QueueExpiry::Ttl(time) => created + time <= now,
+            QueueExpiry::Attempts(count) => self.retry.inner >= count,
+        }
+    }
+}
+
+pub trait SpawnQueue {
+    fn spawn(self, core: Arc<Inner>);
+}
+
+impl QueueStats {
+    pub(crate) fn new(max_in_flight: usize) -> Self {
+        QueueStats {
+            in_flight: 0,
+            max_in_flight,
+            budget: 0,
+            last_warning: Instant::now()
+                .checked_sub(BACK_PRESSURE_WARN_INTERVAL)
+                .unwrap_or_else(Instant::now),
+        }
+    }
+
+    #[inline]
+    pub fn has_capacity(&self) -> bool {
+        self.in_flight < self.max_in_flight
+    }
+}

crates/smtp/src/queue/mod.rs

@@ -0,0 +1,666 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use common::{
+    config::smtp::queue::{QueueExpiry, QueueName},
+    expr::{self, functions::ResolveVariable, *},
+};
+use compact_str::ToCompactString;
+use registry::schema::enums::ExpressionVariable;
+use smtp_proto::Response;
+use std::{
+    fmt::Display,
+    net::{IpAddr, Ipv4Addr},
+    time::{Duration, Instant, SystemTime},
+};
+use store::write::now;
+use types::blob_hash::BlobHash;
+use utils::DomainPart;
+
+pub mod dsn;
+pub mod manager;
+pub mod quota;
+pub mod spool;
+pub mod throttle;
+
+pub type QueueId = u64;
+
+#[derive(Debug, Clone, rkyv::Serialize, rkyv::Deserialize, rkyv::Archive, serde::Deserialize)]
+pub struct Schedule<T> {
+    pub due: u64,
+    pub inner: T,
+}
+
+#[derive(Debug, Clone, Copy)]
+pub struct QueuedMessage {
+    pub due: u64,
+    pub queue_id: QueueId,
+    pub queue_name: QueueName,
+}
+
+#[derive(Debug, Clone, Copy)]
+pub enum MessageSource {
+    Authenticated,
+    Unauthenticated { dmarc_pass: bool },
+    Dsn,
+    Report,
+    Autogenerated,
+}
+
+impl MessageSource {
+    pub fn flags(&self) -> u64 {
+        match self {
+            MessageSource::Authenticated => FROM_AUTHENTICATED,
+            MessageSource::Unauthenticated { dmarc_pass: true } => FROM_UNAUTHENTICATED_DMARC,
+            MessageSource::Unauthenticated { dmarc_pass: false } => FROM_UNAUTHENTICATED,
+            MessageSource::Dsn => FROM_DSN,
+            MessageSource::Report => FROM_REPORT,
+            MessageSource::Autogenerated => FROM_AUTOGENERATED,
+        }
+    }
+}
+
+#[derive(rkyv::Serialize, rkyv::Deserialize, rkyv::Archive, Debug, Clone, PartialEq, Eq)]
+pub struct Message {
+    pub created: u64,
+    pub blob_hash: BlobHash,
+
+    pub return_path: Box<str>,
+    pub recipients: Vec<Recipient>,
+
+    pub received_from_ip: IpAddr,
+    pub received_via_port: u16,
+
+    pub flags: u64,
+    pub env_id: Option<Box<str>>,
+    pub priority: i16,
+
+    pub size: u64,
+    pub metadata: Box<[Metadata]>,
+}
+
+impl Message {
+    pub fn queued_event(&self) -> trc::QueueEvent {
+        if (self.flags & FROM_AUTHENTICATED) != 0 {
+            trc::QueueEvent::AuthenticatedMessageQueued
+        } else if (self.flags & FROM_DSN) != 0 {
+            trc::QueueEvent::DsnQueued
+        } else if (self.flags & FROM_REPORT) != 0 {
+            trc::QueueEvent::ReportQueued
+        } else if (self.flags & FROM_AUTOGENERATED) != 0 {
+            trc::QueueEvent::AutogeneratedQueued
+        } else {
+            trc::QueueEvent::MessageQueued
+        }
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct MessageWrapper {
+    pub queue_id: QueueId,
+    pub queue_name: QueueName,
+    pub is_multi_queue: bool,
+    pub span_id: u64,
+    pub message: Message,
+}
+
+#[derive(
+    rkyv::Serialize,
+    rkyv::Deserialize,
+    rkyv::Archive,
+    Debug,
+    Clone,
+    PartialEq,
+    Eq,
+    serde::Deserialize,
+)]
+pub enum Metadata {
+    QueueSize { key: Box<[u8]>, id: u64 },
+    QueueCount { key: Box<[u8]>, id: u64 },
+    Headers { value: Box<[u8]>, id: u64 },
+}
+
+#[derive(
+    rkyv::Serialize,
+    rkyv::Deserialize,
+    rkyv::Archive,
+    Debug,
+    Clone,
+    PartialEq,
+    Eq,
+    serde::Deserialize,
+)]
+pub struct Recipient {
+    pub address: Box<str>,
+
+    pub retry: Schedule<u32>,
+    pub notify: Schedule<u32>,
+    pub expires: QueueExpiry,
+
+    pub queue: QueueName,
+    pub status: Status<HostResponse<Box<str>>, ErrorDetails>,
+    pub flags: u64,
+    pub orcpt: Option<Box<str>>,
+}
+
+pub const FROM_AUTHENTICATED: u64 = 1 << 32;
+pub const FROM_UNAUTHENTICATED: u64 = 1 << 33;
+pub const FROM_UNAUTHENTICATED_DMARC: u64 = 1 << 34;
+pub const FROM_DSN: u64 = 1 << 35;
+pub const FROM_REPORT: u64 = 1 << 36;
+pub const FROM_AUTOGENERATED: u64 = 1 << 37;
+
+pub const RCPT_DSN_SENT: u64 = 1 << 32;
+
+pub const RCPT_SPAM_SHIFT: u64 = 56;
+pub const RCPT_SPAM_MASK: u64 = 0xff << RCPT_SPAM_SHIFT;
+
+pub const fn rcpt_spam_flag(percentage: u8) -> u64 {
+    (percentage as u64 + 1) << RCPT_SPAM_SHIFT
+}
+
+pub const fn rcpt_spam_percentage(flags: u64) -> Option<u8> {
+    match (flags >> RCPT_SPAM_SHIFT) as u8 {
+        0 => None,
+        percentage => Some(percentage - 1),
+    }
+}
+
+#[derive(
+    Debug,
+    Clone,
+    PartialEq,
+    Eq,
+    rkyv::Serialize,
+    rkyv::Deserialize,
+    rkyv::Archive,
+    serde::Serialize,
+    serde::Deserialize,
+)]
+pub enum Status<T, E> {
+    #[serde(rename = "scheduled")]
+    Scheduled,
+    #[serde(rename = "completed")]
+    Completed(T),
+    #[serde(rename = "temp_fail")]
+    TemporaryFailure(E),
+    #[serde(rename = "perm_fail")]
+    PermanentFailure(E),
+}
+
+#[derive(
+    Debug,
+    Clone,
+    PartialEq,
+    Eq,
+    rkyv::Serialize,
+    rkyv::Deserialize,
+    rkyv::Archive,
+    serde::Deserialize,
+)]
+pub struct HostResponse<T> {
+    pub hostname: T,
+    pub response: Response<Box<str>>,
+}
+
+#[derive(
+    Debug,
+    Clone,
+    PartialEq,
+    Eq,
+    rkyv::Serialize,
+    rkyv::Deserialize,
+    rkyv::Archive,
+    serde::Deserialize,
+    Default,
+)]
+pub enum Error {
+    DnsError(Box<str>),
+    UnexpectedResponse(UnexpectedResponse),
+    ConnectionError(Box<str>),
+    TlsError(Box<str>),
+    DaneError(Box<str>),
+    MtaStsError(Box<str>),
+    RateLimited,
+    #[default]
+    ConcurrencyLimited,
+    Io(Box<str>),
+}
+
+#[derive(
+    Debug,
+    Clone,
+    PartialEq,
+    Eq,
+    rkyv::Serialize,
+    rkyv::Deserialize,
+    rkyv::Archive,
+    serde::Deserialize,
+)]
+pub struct UnexpectedResponse {
+    pub command: Box<str>,
+    pub response: Response<Box<str>>,
+}
+
+#[derive(
+    Debug,
+    Clone,
+    PartialEq,
+    Eq,
+    rkyv::Serialize,
+    rkyv::Deserialize,
+    rkyv::Archive,
+    Default,
+    serde::Deserialize,
+)]
+pub struct ErrorDetails {
+    pub entity: Box<str>,
+    pub details: Error,
+}
+
+impl<T> Ord for Schedule<T> {
+    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
+        other.due.cmp(&self.due)
+    }
+}
+
+impl<T> PartialOrd for Schedule<T> {
+    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+impl<T> PartialEq for Schedule<T> {
+    fn eq(&self, other: &Self) -> bool {
+        self.due == other.due
+    }
+}
+
+impl<T> Eq for Schedule<T> {}
+
+impl<T: Default> Schedule<T> {
+    pub fn now() -> Self {
+        Schedule {
+            due: now(),
+            inner: T::default(),
+        }
+    }
+
+    pub fn later(duration: u64) -> Self {
+        Schedule {
+            due: now() + duration,
+            inner: T::default(),
+        }
+    }
+}
+
+pub struct QueueEnvelope<'x> {
+    pub message: &'x Message,
+    pub domain: &'x str,
+    pub mx: &'x str,
+    pub rcpt: &'x Recipient,
+    pub remote_ip: IpAddr,
+    pub local_ip: IpAddr,
+}
+
+impl<'x> QueueEnvelope<'x> {
+    pub fn new(message: &'x Message, rcpt: &'x Recipient) -> Self {
+        Self {
+            message,
+            domain: rcpt.address.domain_part(),
+            rcpt,
+            mx: "",
+            remote_ip: IpAddr::V4(Ipv4Addr::new(0, 0, 0, 0)),
+            local_ip: IpAddr::V4(Ipv4Addr::new(0, 0, 0, 0)),
+        }
+    }
+}
+
+impl<'x> ResolveVariable for QueueEnvelope<'x> {
+    fn resolve_variable(&self, variable: ExpressionVariable) -> expr::Variable<'x> {
+        match variable {
+            ExpressionVariable::Sender => self.message.return_path.as_ref().into(),
+            ExpressionVariable::SenderDomain => self.message.return_path.domain_part().into(),
+            ExpressionVariable::RcptDomain => self.domain.into(),
+            ExpressionVariable::Rcpt => self.rcpt.address.as_ref().into(),
+            ExpressionVariable::Recipients => self
+                .message
+                .recipients
+                .iter()
+                .map(|r| Variable::from(r.address.as_ref()))
+                .collect::<Vec<_>>()
+                .into(),
+            ExpressionVariable::RetryNum => self.rcpt.retry.inner.into(),
+            ExpressionVariable::NotifyNum => self.rcpt.notify.inner.into(),
+            ExpressionVariable::ExpiresIn => match &self.rcpt.expires {
+                QueueExpiry::Ttl(time) => (*time + self.message.created).saturating_sub(now()),
+                QueueExpiry::Attempts(count) => {
+                    (count.saturating_sub(self.rcpt.retry.inner)) as u64
+                }
+            }
+            .into(),
+            ExpressionVariable::LastStatus => self.rcpt.status.to_compact_string().into(),
+            ExpressionVariable::LastError => match &self.rcpt.status {
+                Status::Scheduled | Status::Completed(_) => "none",
+                Status::TemporaryFailure(err) | Status::PermanentFailure(err) => {
+                    match &err.details {
+                        Error::DnsError(_) => "dns",
+                        Error::UnexpectedResponse(_) => "unexpected-reply",
+                        Error::ConnectionError(_) => "connection",
+                        Error::TlsError(_) => "tls",
+                        Error::DaneError(_) => "dane",
+                        Error::MtaStsError(_) => "mta-sts",
+                        Error::RateLimited => "rate",
+                        Error::ConcurrencyLimited => "concurrency",
+                        Error::Io(_) => "io",
+                    }
+                }
+            }
+            .into(),
+            ExpressionVariable::QueueName => self.rcpt.queue.as_str().into(),
+            ExpressionVariable::QueueAge => now().saturating_sub(self.message.created).into(),
+            ExpressionVariable::Source => if (self.message.flags & FROM_AUTHENTICATED) != 0 {
+                "authenticated"
+            } else if (self.message.flags & FROM_UNAUTHENTICATED_DMARC) != 0 {
+                "dmarc_pass"
+            } else if (self.message.flags & FROM_UNAUTHENTICATED) != 0 {
+                "unauthenticated"
+            } else if (self.message.flags & FROM_DSN) != 0 {
+                "dsn"
+            } else if (self.message.flags & FROM_REPORT) != 0 {
+                "report"
+            } else if (self.message.flags & FROM_AUTOGENERATED) != 0 {
+                "autogenerated"
+            } else {
+                "unknown"
+            }
+            .into(),
+            ExpressionVariable::Mx => self.mx.into(),
+            ExpressionVariable::Priority => self.message.priority.into(),
+            ExpressionVariable::RemoteIp => self.remote_ip.to_compact_string().into(),
+            ExpressionVariable::LocalIp => self.local_ip.to_compact_string().into(),
+            ExpressionVariable::ReceivedFromIp => {
+                self.message.received_from_ip.to_compact_string().into()
+            }
+            ExpressionVariable::ReceivedViaPort => self.message.received_via_port.into(),
+            ExpressionVariable::Size => self.message.size.into(),
+            _ => "".into(),
+        }
+    }
+
+    fn resolve_global(&self, _: &str) -> Variable<'_> {
+        Variable::Integer(0)
+    }
+}
+
+impl ResolveVariable for Message {
+    fn resolve_variable(&self, variable: ExpressionVariable) -> expr::Variable<'_> {
+        match variable {
+            ExpressionVariable::Sender => self.return_path.as_ref().into(),
+            ExpressionVariable::SenderDomain => self.return_path.domain_part().into(),
+            ExpressionVariable::Recipients => self
+                .recipients
+                .iter()
+                .map(|r| Variable::from(r.address.as_ref()))
+                .collect::<Vec<_>>()
+                .into(),
+            ExpressionVariable::Priority => self.priority.into(),
+            _ => "".into(),
+        }
+    }
+
+    fn resolve_global(&self, _: &str) -> Variable<'_> {
+        Variable::Integer(0)
+    }
+}
+
+impl ResolveVariable for MessageWrapper {
+    fn resolve_variable(&self, variable: ExpressionVariable) -> expr::Variable<'_> {
+        match variable {
+            ExpressionVariable::Sender => self.message.return_path.as_ref().into(),
+            ExpressionVariable::SenderDomain => self.message.return_path.domain_part().into(),
+            ExpressionVariable::Recipients => self
+                .message
+                .recipients
+                .iter()
+                .map(|r| Variable::from(r.address.as_ref()))
+                .collect::<Vec<_>>()
+                .into(),
+            ExpressionVariable::Priority => self.message.priority.into(),
+            ExpressionVariable::QueueName => self.queue_name.as_str().into(),
+            ExpressionVariable::QueueAge => now().saturating_sub(self.message.created).into(),
+            ExpressionVariable::Source => if (self.message.flags & FROM_AUTHENTICATED) != 0 {
+                "authenticated"
+            } else if (self.message.flags & FROM_UNAUTHENTICATED_DMARC) != 0 {
+                "dmarc_pass"
+            } else if (self.message.flags & FROM_UNAUTHENTICATED) != 0 {
+                "unauthenticated"
+            } else if (self.message.flags & FROM_DSN) != 0 {
+                "dsn"
+            } else if (self.message.flags & FROM_REPORT) != 0 {
+                "report"
+            } else if (self.message.flags & FROM_AUTOGENERATED) != 0 {
+                "autogenerated"
+            } else {
+                "unknown"
+            }
+            .into(),
+            ExpressionVariable::ReceivedFromIp => {
+                self.message.received_from_ip.to_compact_string().into()
+            }
+            ExpressionVariable::ReceivedViaPort => self.message.received_via_port.into(),
+            ExpressionVariable::Size => self.message.size.into(),
+            _ => "".into(),
+        }
+    }
+
+    fn resolve_global(&self, _: &str) -> Variable<'_> {
+        Variable::Integer(0)
+    }
+}
+
+pub struct RecipientDomain<'x>(&'x str);
+
+impl<'x> RecipientDomain<'x> {
+    pub fn new(domain: &'x str) -> Self {
+        Self(domain)
+    }
+}
+
+impl<'x> ResolveVariable for RecipientDomain<'x> {
+    fn resolve_variable(&self, variable: ExpressionVariable) -> expr::Variable<'x> {
+        match variable {
+            ExpressionVariable::RcptDomain => self.0.into(),
+            _ => "".into(),
+        }
+    }
+
+    fn resolve_global(&self, _: &str) -> Variable<'_> {
+        Variable::Integer(0)
+    }
+}
+
+#[inline(always)]
+pub fn instant_to_timestamp(now: Instant, time: Instant) -> u64 {
+    SystemTime::now()
+        .duration_since(SystemTime::UNIX_EPOCH)
+        .map_or(0, |d| d.as_secs())
+        + time.checked_duration_since(now).map_or(0, |d| d.as_secs())
+}
+
+impl Recipient {
+    pub fn new(address: impl AsRef<str>) -> Self {
+        Recipient {
+            address: address.to_lowercase_address(false).into_boxed_str(),
+            status: Status::Scheduled,
+            flags: 0,
+            orcpt: None,
+            retry: Schedule::now(),
+            notify: Schedule::now(),
+            expires: QueueExpiry::Attempts(0),
+            queue: QueueName::default(),
+        }
+    }
+
+    pub fn with_flags(mut self, flags: u64) -> Self {
+        self.flags = flags;
+        self
+    }
+
+    pub fn with_orcpt(mut self, orcpt: Option<Box<str>>) -> Self {
+        self.orcpt = orcpt;
+        self
+    }
+
+    pub fn address(&self) -> &str {
+        &self.address
+    }
+
+    pub fn domain_part(&self) -> &str {
+        self.address.domain_part()
+    }
+}
+
+impl ArchivedRecipient {
+    pub fn address(&self) -> &str {
+        self.address.as_ref()
+    }
+
+    pub fn domain_part(&self) -> &str {
+        self.address.domain_part()
+    }
+}
+
+pub trait InstantFromTimestamp {
+    fn to_instant(&self) -> Instant;
+}
+
+impl InstantFromTimestamp for u64 {
+    fn to_instant(&self) -> Instant {
+        let timestamp = *self;
+        let current_timestamp = SystemTime::now()
+            .duration_since(SystemTime::UNIX_EPOCH)
+            .map_or(0, |d| d.as_secs());
+        if timestamp > current_timestamp {
+            Instant::now() + Duration::from_secs(timestamp - current_timestamp)
+        } else {
+            Instant::now()
+        }
+    }
+}
+
+impl Display for Error {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Error::UnexpectedResponse(response) => {
+                write!(
+                    f,
+                    "Unexpected response for {}: {}",
+                    response.command, response.response
+                )
+            }
+            Error::DnsError(err) => {
+                write!(f, "DNS lookup failed: {err}")
+            }
+            Error::ConnectionError(details) => {
+                write!(f, "Connection failed: {details}",)
+            }
+            Error::TlsError(details) => {
+                write!(f, "TLS error: {details}",)
+            }
+            Error::DaneError(details) => {
+                write!(f, "DANE authentication failure: {details}",)
+            }
+            Error::MtaStsError(details) => {
+                write!(f, "MTA-STS auth failed: {details}")
+            }
+            Error::RateLimited => {
+                write!(f, "Rate limited")
+            }
+            Error::ConcurrencyLimited => {
+                write!(f, "Too many concurrent connections to remote server")
+            }
+            Error::Io(err) => {
+                write!(f, "Queue error: {err}")
+            }
+        }
+    }
+}
+
+impl Display for ArchivedError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            ArchivedError::UnexpectedResponse(response) => {
+                write!(
+                    f,
+                    "Unexpected response for {}: {}",
+                    response.command, response.response
+                )
+            }
+            ArchivedError::DnsError(err) => {
+                write!(f, "DNS lookup failed: {err}")
+            }
+            ArchivedError::ConnectionError(details) => {
+                write!(f, "Connection failed: {details}",)
+            }
+            ArchivedError::TlsError(details) => {
+                write!(f, "TLS error: {details}",)
+            }
+            ArchivedError::DaneError(details) => {
+                write!(f, "DANE authentication failure: {details}",)
+            }
+            ArchivedError::MtaStsError(details) => {
+                write!(f, "MTA-STS auth failed: {details}")
+            }
+            ArchivedError::RateLimited => {
+                write!(f, "Rate limited")
+            }
+            ArchivedError::ConcurrencyLimited => {
+                write!(f, "Too many concurrent connections to remote server")
+            }
+            ArchivedError::Io(err) => {
+                write!(f, "Queue error: {err}")
+            }
+        }
+    }
+}
+
+impl Display for Status<HostResponse<Box<str>>, ErrorDetails> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Status::Scheduled => write!(f, "Scheduled"),
+            Status::Completed(response) => write!(f, "Delivered: {}", response.response),
+            Status::TemporaryFailure(err) => {
+                write!(f, "Temporary Failure for {}: {}", err.entity, err.details)
+            }
+            Status::PermanentFailure(err) => {
+                write!(f, "Permanent Failure for {}: {}", err.entity, err.details)
+            }
+        }
+    }
+}
+
+impl Display for ArchivedErrorDetails {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "Error for {}: {}", self.entity, self.details)
+    }
+}
+
+/*
+
+pub trait DisplayArchivedResponse {
+    fn to_string(&self) -> String;
+}
+
+impl DisplayArchivedResponse for ArchivedResponse<Box<str>> {
+    fn to_string(&self) -> String {
+        format!(
+            "Code: {}, Enhanced code: {}.{}.{}, Message: {}",
+            self.code, self.esc[0], self.esc[1], self.esc[2], self.message,
+        )
+    }
+}
+*/

crates/smtp/src/queue/quota.rs

@@ -0,0 +1,230 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use super::{Metadata, QueueEnvelope, Status};
+use crate::{core::throttle::NewKey, queue::MessageWrapper};
+use ahash::AHashSet;
+use common::{Server, config::smtp::queue::QueueQuota, expr::functions::ResolveVariable};
+use std::future::Future;
+use store::{
+    ValueKey,
+    write::{BatchBuilder, QueueClass, ValueClass},
+};
+use trc::QueueEvent;
+use utils::DomainPart;
+
+pub trait HasQueueQuota: Sync + Send {
+    fn has_quota(
+        &self,
+        message: &mut MessageWrapper,
+    ) -> impl Future<Output = Option<Vec<Metadata>>> + Send;
+    fn check_quota<'x>(
+        &'x self,
+        quota: &'x QueueQuota,
+        envelope: &impl ResolveVariable,
+        size: u64,
+        id: u64,
+        refs: &mut Vec<Metadata>,
+        session_id: u64,
+    ) -> impl Future<Output = bool> + Send;
+}
+
+impl HasQueueQuota for Server {
+    async fn has_quota(&self, message: &mut MessageWrapper) -> Option<Vec<Metadata>> {
+        let mut quota_keys = Vec::new();
+
+        if !self.core.smtp.queue.quota.sender.is_empty() {
+            for quota in &self.core.smtp.queue.quota.sender {
+                if !self
+                    .check_quota(
+                        quota,
+                        &message.message,
+                        message.message.size,
+                        0,
+                        &mut quota_keys,
+                        message.span_id,
+                    )
+                    .await
+                {
+                    trc::event!(
+                        Queue(QueueEvent::QuotaExceeded),
+                        SpanId = message.span_id,
+                        Id = quota.id.to_string(),
+                        Type = "Sender"
+                    );
+
+                    return None;
+                }
+            }
+        }
+
+        if !self.core.smtp.queue.quota.rcpt_domain.is_empty() {
+            let mut seen_domains = AHashSet::new();
+            for quota in &self.core.smtp.queue.quota.rcpt_domain {
+                for (rcpt_idx, rcpt) in message.message.recipients.iter().enumerate() {
+                    if seen_domains.insert(rcpt.address.domain_part())
+                        && !self
+                            .check_quota(
+                                quota,
+                                &QueueEnvelope::new(&message.message, rcpt),
+                                message.message.size,
+                                ((rcpt_idx + 1) << 32) as u64,
+                                &mut quota_keys,
+                                message.span_id,
+                            )
+                            .await
+                    {
+                        trc::event!(
+                            Queue(QueueEvent::QuotaExceeded),
+                            SpanId = message.span_id,
+                            Id = quota.id.to_string(),
+                            Type = "Domain"
+                        );
+
+                        return None;
+                    }
+                }
+            }
+        }
+
+        for quota in &self.core.smtp.queue.quota.rcpt {
+            for (rcpt_idx, rcpt) in message.message.recipients.iter().enumerate() {
+                if !self
+                    .check_quota(
+                        quota,
+                        &QueueEnvelope::new(&message.message, rcpt),
+                        message.message.size,
+                        (rcpt_idx + 1) as u64,
+                        &mut quota_keys,
+                        message.span_id,
+                    )
+                    .await
+                {
+                    trc::event!(
+                        Queue(QueueEvent::QuotaExceeded),
+                        SpanId = message.span_id,
+                        Id = quota.id.to_string(),
+                        Type = "Recipient"
+                    );
+
+                    return None;
+                }
+            }
+        }
+
+        Some(quota_keys)
+    }
+
+    async fn check_quota<'x>(
+        &'x self,
+        quota: &'x QueueQuota,
+        envelope: &impl ResolveVariable,
+        size: u64,
+        id: u64,
+        refs: &mut Vec<Metadata>,
+        session_id: u64,
+    ) -> bool {
+        if !quota.expr.is_empty()
+            && self
+                .eval_if(&quota.expr, envelope, session_id)
+                .await
+                .unwrap_or(false)
+        {
+            let key = quota.new_key(envelope, "");
+            if let Some(max_size) = quota.size {
+                let used_size = self
+                    .core
+                    .storage
+                    .data
+                    .get_counter(ValueKey::from(ValueClass::Queue(QueueClass::QuotaSize(
+                        key.as_ref().to_vec(),
+                    ))))
+                    .await
+                    .unwrap_or(0) as u64;
+                if used_size + size > max_size {
+                    return false;
+                } else {
+                    refs.push(Metadata::QueueSize {
+                        key: key.as_ref().into(),
+                        id,
+                    });
+                }
+            }
+
+            if let Some(max_messages) = quota.messages {
+                let total_messages = self
+                    .core
+                    .storage
+                    .data
+                    .get_counter(ValueKey::from(ValueClass::Queue(QueueClass::QuotaCount(
+                        key.as_ref().to_vec(),
+                    ))))
+                    .await
+                    .unwrap_or(0) as u64;
+                if total_messages + 1 > max_messages {
+                    return false;
+                } else {
+                    refs.push(Metadata::QueueCount {
+                        key: key.as_ref().into(),
+                        id,
+                    });
+                }
+            }
+        }
+        true
+    }
+}
+
+impl MessageWrapper {
+    pub fn release_quota(&mut self, batch: &mut BatchBuilder) {
+        if !self.message.metadata.iter().any(|metadata| {
+            matches!(
+                metadata,
+                Metadata::QueueSize { .. } | Metadata::QueueCount { .. }
+            )
+        }) {
+            return;
+        }
+        let mut quota_ids = Vec::with_capacity(self.message.recipients.len());
+
+        let mut seen_domains = AHashSet::new();
+        for (pos, rcpt) in self.message.recipients.iter().enumerate() {
+            if matches!(
+                &rcpt.status,
+                Status::Completed(_) | Status::PermanentFailure(_)
+            ) {
+                if seen_domains.insert(rcpt.address.domain_part()) {
+                    quota_ids.push(((pos + 1) as u64) << 32);
+                }
+                quota_ids.push((pos + 1) as u64);
+            }
+        }
+
+        if !quota_ids.is_empty() {
+            let mut metadata = Vec::new();
+            for entry in std::mem::take(&mut self.message.metadata) {
+                match entry {
+                    Metadata::QueueCount { id, key } if quota_ids.contains(&id) => {
+                        batch.add(
+                            ValueClass::Queue(QueueClass::QuotaCount(key.into_vec())),
+                            -1,
+                        );
+                    }
+                    Metadata::QueueSize { id, key } if quota_ids.contains(&id) => {
+                        batch.add(
+                            ValueClass::Queue(QueueClass::QuotaSize(key.into_vec())),
+                            -(self.message.size as i64),
+                        );
+                    }
+                    _ => {
+                        metadata.push(entry);
+                    }
+                }
+            }
+            self.message.metadata = metadata.into_boxed_slice();
+        }
+    }
+}

crates/smtp/src/queue/throttle.rs

@@ -0,0 +1,65 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use crate::core::throttle::NewKey;
+use common::{
+    KV_RATE_LIMIT_SMTP, Server, config::smtp::QueueRateLimiter, expr::functions::ResolveVariable,
+};
+use std::future::Future;
+use store::write::now;
+
+pub trait IsAllowed: Sync + Send {
+    fn is_allowed<'x>(
+        &'x self,
+        throttle: &'x QueueRateLimiter,
+        envelope: &impl ResolveVariable,
+        session_id: u64,
+    ) -> impl Future<Output = Result<(), u64>> + Send;
+}
+
+impl IsAllowed for Server {
+    async fn is_allowed<'x>(
+        &'x self,
+        throttle: &'x QueueRateLimiter,
+        envelope: &impl ResolveVariable,
+        session_id: u64,
+    ) -> Result<(), u64> {
+        if throttle.expr.is_empty()
+            || self
+                .eval_if(&throttle.expr, envelope, session_id)
+                .await
+                .unwrap_or(false)
+        {
+            let key = throttle.new_key(envelope, "outbound");
+
+            match self
+                .in_memory_store()
+                .is_rate_allowed(KV_RATE_LIMIT_SMTP, key.as_ref(), &throttle.rate, false)
+                .await
+            {
+                Ok(Some(next_refill)) => {
+                    trc::event!(
+                        Queue(trc::QueueEvent::RateLimitExceeded),
+                        SpanId = session_id,
+                        Id = throttle.id.to_string(),
+                        Limit = vec![
+                            trc::Value::from(throttle.rate.count),
+                            trc::Value::from(throttle.rate.period.into_inner())
+                        ],
+                    );
+
+                    return Err(now() + next_refill);
+                }
+                Err(err) => {
+                    trc::error!(err.span_id(session_id).caused_by(trc::location!()));
+                }
+                _ => (),
+            }
+        }
+
+        Ok(())
+    }
+}

crates/smtp/src/reporting/analysis.rs

@@ -0,0 +1,412 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use ahash::AHashSet;
+use common::{Server, psl};
+use mail_auth::{
+    flate2::read::GzDecoder,
+    report::{Feedback, Report, tlsrpt::TlsReport},
+    zip,
+};
+use mail_parser::{Message, MessagePart, MimeHeaders, PartType};
+use registry::{
+    schema::structs::{ArfExternalReport, DmarcExternalReport, TlsExternalReport},
+    types::datetime::UTCDateTime,
+};
+use std::{
+    borrow::Cow,
+    io::{Cursor, Read},
+};
+use store::write::{BatchBuilder, now};
+use trc::IncomingReportEvent;
+use types::id::Id;
+
+use crate::reporting::{inbound::LogReport, index::ExternalReportIndex};
+
+enum Compression {
+    None,
+    Gzip,
+    Zip,
+}
+
+enum Format<D, T, A> {
+    Dmarc(D),
+    Tls(T),
+    Arf(A),
+}
+
+pub(crate) struct ReportData<'x> {
+    compression: Compression,
+    format: Format<(), (), ()>,
+    data: &'x [u8],
+}
+
+impl<'x> ReportData<'x> {
+    fn from_part(part: &'x MessagePart<'x>) -> Option<Self> {
+        match &part.body {
+            PartType::Text(report) => {
+                if part
+                    .content_type()
+                    .and_then(|ct| ct.subtype())
+                    .is_some_and(|t| t.eq_ignore_ascii_case("xml"))
+                    || part
+                        .attachment_name()
+                        .and_then(|n| n.rsplit_once('.'))
+                        .is_some_and(|(_, e)| e.eq_ignore_ascii_case("xml"))
+                {
+                    Some(ReportData {
+                        compression: Compression::None,
+                        format: Format::Dmarc(()),
+                        data: report.as_bytes(),
+                    })
+                } else if part.is_content_type("message", "feedback-report") {
+                    Some(ReportData {
+                        compression: Compression::None,
+                        format: Format::Arf(()),
+                        data: report.as_bytes(),
+                    })
+                } else {
+                    None
+                }
+            }
+            PartType::Binary(report) | PartType::InlineBinary(report) => {
+                if part.is_content_type("message", "feedback-report") {
+                    return Some(ReportData {
+                        compression: Compression::None,
+                        format: Format::Arf(()),
+                        data: report.as_ref(),
+                    });
+                }
+
+                let subtype = part
+                    .content_type()
+                    .and_then(|ct| ct.subtype())
+                    .unwrap_or("");
+                let attachment_name = part.attachment_name();
+                let ext = attachment_name
+                    .and_then(|f| f.rsplit_once('.'))
+                    .map_or("", |(_, e)| e);
+                let tls_parts = subtype.rsplit_once('+');
+                let compression = match (tls_parts.map(|(_, c)| c).unwrap_or(subtype), ext) {
+                    ("gzip", _) => Compression::Gzip,
+                    ("zip", _) => Compression::Zip,
+                    (_, "gz") => Compression::Gzip,
+                    (_, "zip") => Compression::Zip,
+                    _ => Compression::None,
+                };
+                let format = match (tls_parts.map(|(c, _)| c).unwrap_or(subtype), ext) {
+                    ("xml", _) => Format::Dmarc(()),
+                    ("tlsrpt", _) | (_, "json") => Format::Tls(()),
+                    _ => {
+                        if attachment_name.is_some_and(|n| n.contains(".xml") || n.contains('!')) {
+                            Format::Dmarc(())
+                        } else {
+                            return None;
+                        }
+                    }
+                };
+
+                Some(ReportData {
+                    compression,
+                    format,
+                    data: report.as_ref(),
+                })
+            }
+            _ => None,
+        }
+    }
+
+    fn extract(message: &'x Message<'x>) -> Vec<Self> {
+        message.parts.iter().filter_map(Self::from_part).collect()
+    }
+
+    pub(crate) fn is_present(message: &Message<'_>) -> bool {
+        message
+            .parts
+            .iter()
+            .any(|part| ReportData::from_part(part).is_some())
+    }
+}
+
+pub trait AnalyzeReport: Sync + Send {
+    fn analyze_report(&self, message: Message<'static>, session_id: u64);
+}
+
+impl AnalyzeReport for Server {
+    fn analyze_report(&self, message: Message<'static>, session_id: u64) {
+        let core = self.clone();
+        tokio::spawn(async move {
+            let from: String = message
+                .from()
+                .and_then(|a| a.last())
+                .and_then(|a| a.address())
+                .unwrap_or_default()
+                .into();
+            let to: Vec<String> = message.to().map_or_else(Vec::new, |a| {
+                a.iter()
+                    .filter_map(|a| a.address())
+                    .map(|a| a.into())
+                    .collect()
+            });
+            let subject: String = message.subject().unwrap_or_default().into();
+            let reports = ReportData::extract(&message);
+            let max_size = core.core.smtp.report.analysis.max_size;
+
+            for report in reports {
+                let data = match report.compression {
+                    Compression::None => Cow::Borrowed(report.data),
+                    Compression::Gzip => {
+                        match read_capped(GzDecoder::new(report.data), 0, max_size) {
+                            Ok(buf) => Cow::Owned(buf),
+                            Err(err) => {
+                                trc::event!(
+                                    IncomingReport(IncomingReportEvent::DecompressError),
+                                    SpanId = session_id,
+                                    From = from.to_string(),
+                                    Reason = err.to_string(),
+                                    CausedBy = trc::location!()
+                                );
+
+                                continue;
+                            }
+                        }
+                    }
+                    Compression::Zip => {
+                        let data = report.data.to_vec();
+                        let result = tokio::task::spawn_blocking(
+                            move || -> Result<Vec<u8>, std::io::Error> {
+                                let mut archive = zip::ZipArchive::new(Cursor::new(data))
+                                    .map_err(std::io::Error::other)?;
+                                if archive.is_empty() {
+                                    return Ok(Vec::new());
+                                }
+                                let mut file =
+                                    archive.by_index(0).map_err(std::io::Error::other)?;
+                                let size_hint = file.size();
+                                read_capped(&mut file, size_hint, max_size)
+                            },
+                        )
+                        .await;
+                        match result {
+                            Ok(Ok(buf)) => Cow::Owned(buf),
+                            Ok(Err(err)) => {
+                                trc::event!(
+                                    IncomingReport(IncomingReportEvent::DecompressError),
+                                    SpanId = session_id,
+                                    From = from.to_string(),
+                                    Reason = err.to_string(),
+                                    CausedBy = trc::location!()
+                                );
+                                continue;
+                            }
+                            Err(err) => {
+                                trc::event!(
+                                    IncomingReport(IncomingReportEvent::DecompressError),
+                                    SpanId = session_id,
+                                    From = from.to_string(),
+                                    Reason = err.to_string(),
+                                    CausedBy = trc::location!()
+                                );
+                                continue;
+                            }
+                        }
+                    }
+                };
+
+                let report = match report.format {
+                    Format::Dmarc(_) => match Report::parse_xml(&data) {
+                        Ok(report) => {
+                            // Log
+                            report.log();
+                            Format::Dmarc(report)
+                        }
+                        Err(err) => {
+                            trc::event!(
+                                IncomingReport(IncomingReportEvent::DmarcParseFailed),
+                                SpanId = session_id,
+                                From = from.to_string(),
+                                Reason = err,
+                                CausedBy = trc::location!()
+                            );
+
+                            continue;
+                        }
+                    },
+                    Format::Tls(_) => match TlsReport::parse_json(&data) {
+                        Ok(report) => {
+                            // Log
+                            report.log();
+                            Format::Tls(report)
+                        }
+                        Err(err) => {
+                            trc::event!(
+                                IncomingReport(IncomingReportEvent::TlsRpcParseFailed),
+                                SpanId = session_id,
+                                From = from.to_string(),
+                                Reason = format!("{err:?}"),
+                                CausedBy = trc::location!()
+                            );
+
+                            continue;
+                        }
+                    },
+                    Format::Arf(_) => match Feedback::parse_arf(&data) {
+                        Some(report) => {
+                            // Log
+                            report.log();
+                            Format::Arf(report.into_owned())
+                        }
+                        None => {
+                            trc::event!(
+                                IncomingReport(IncomingReportEvent::ArfParseFailed),
+                                SpanId = session_id,
+                                From = from.to_string(),
+                                CausedBy = trc::location!()
+                            );
+
+                            continue;
+                        }
+                    },
+                };
+
+                // Store report
+                if let Some(expires_in) = &core.core.smtp.report.analysis.store {
+                    let expires = now() + expires_in.as_secs();
+                    let item_id = core.inner.data.queue_id_gen.generate();
+                    let mut batch = BatchBuilder::new();
+
+                    match report {
+                        Format::Dmarc(report) => {
+                            let mut report = DmarcExternalReport {
+                                from,
+                                to: to.into(),
+                                subject,
+                                member_tenant_id: None,
+                                expires_at: UTCDateTime::from_timestamp(expires as i64),
+                                received_at: UTCDateTime::now(),
+                                report: report.into(),
+                            };
+                            report.member_tenant_id = tenant_ids(
+                                &core,
+                                report
+                                    .domains()
+                                    .filter_map(psl::domain_str)
+                                    .collect::<AHashSet<_>>(),
+                            )
+                            .await;
+                            report.write_ops(&mut batch, item_id, true);
+                        }
+                        Format::Tls(report) => {
+                            let mut report = TlsExternalReport {
+                                from,
+                                to: to.into(),
+                                subject,
+                                member_tenant_id: None,
+                                expires_at: UTCDateTime::from_timestamp(expires as i64),
+                                received_at: UTCDateTime::now(),
+                                report: report.into(),
+                            };
+                            report.member_tenant_id = tenant_ids(
+                                &core,
+                                report
+                                    .domains()
+                                    .filter_map(psl::domain_str)
+                                    .collect::<AHashSet<_>>(),
+                            )
+                            .await;
+                            report.write_ops(&mut batch, item_id, true);
+                        }
+                        Format::Arf(report) => {
+                            let mut report = ArfExternalReport {
+                                from,
+                                to: to.into(),
+                                subject,
+                                member_tenant_id: None,
+                                expires_at: UTCDateTime::from_timestamp(expires as i64),
+                                received_at: UTCDateTime::now(),
+                                report: report.into(),
+                            };
+                            report.member_tenant_id = tenant_ids(
+                                &core,
+                                report
+                                    .domains()
+                                    .filter_map(psl::domain_str)
+                                    .collect::<AHashSet<_>>(),
+                            )
+                            .await;
+                            report.write_ops(&mut batch, item_id, true);
+                        }
+                    }
+
+                    if let Err(err) = core.core.storage.data.write(batch.build_all()).await
+                        && !err.is_assertion_failure()
+                    {
+                        trc::error!(
+                            err.span_id(session_id)
+                                .caused_by(trc::location!())
+                                .details("Failed to write report")
+                        );
+                    }
+                }
+                return;
+            }
+        });
+    }
+}
+
+async fn tenant_ids(server: &Server, domains: AHashSet<&str>) -> Option<Id> {
+    let mut tenant_ids = Vec::with_capacity(domains.len());
+    for domain in domains {
+        if let Some(tenant_id) = server
+            .domain(domain)
+            .await
+            .map_err(|err| {
+                trc::error!(
+                    err.caused_by(trc::location!())
+                        .details("Failed to lookup domain")
+                );
+            })
+            .unwrap_or_default()
+            .and_then(|domain| domain.id_tenant)
+            .map(Id::from)
+            && !tenant_ids.contains(&tenant_id)
+        {
+            tenant_ids.push(tenant_id);
+        }
+    }
+
+    if tenant_ids.len() == 1 {
+        tenant_ids.into_iter().next()
+    } else {
+        None
+    }
+}
+
+fn read_capped(
+    reader: impl Read,
+    size_hint: u64,
+    max_size: usize,
+) -> Result<Vec<u8>, std::io::Error> {
+    let max_size = max_size as u64;
+    if size_hint > max_size {
+        return Err(std::io::Error::other(format!(
+            "Report is larger than the {max_size} byte limit"
+        )));
+    }
+
+    let mut buf = Vec::with_capacity(size_hint.min(64 * 1024) as usize);
+    reader
+        .take(max_size.saturating_add(1))
+        .read_to_end(&mut buf)?;
+
+    if buf.len() as u64 > max_size {
+        return Err(std::io::Error::other(format!(
+            "Report is larger than the {max_size} byte limit"
+        )));
+    }
+
+    Ok(buf)
+}

crates/smtp/src/reporting/dkim.rs

@@ -0,0 +1,109 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use crate::{core::Session, reporting::send::MtaReportSend};
+use common::network::SessionStream;
+use mail_auth::{
+    AuthenticatedMessage, AuthenticationResults, DkimOutput, common::verify::VerifySignature,
+};
+use registry::schema::structs::Rate;
+use trc::OutgoingReportEvent;
+
+impl<T: SessionStream> Session<T> {
+    pub async fn send_dkim_report(
+        &self,
+        rcpt: &str,
+        message: &AuthenticatedMessage<'_>,
+        rate: &Rate,
+        rejected: bool,
+        output: &DkimOutput<'_>,
+    ) {
+        // Generate report
+        let signature = if let Some(signature) = output.signature() {
+            signature
+        } else {
+            return;
+        };
+
+        if self
+            .server
+            .is_local_report_domain(signature.domain(), self.data.session_id)
+            .await
+        {
+            return;
+        }
+
+        // Throttle recipient
+        if !self.throttle_rcpt(rcpt, rate, "dkim").await {
+            trc::event!(
+                OutgoingReport(OutgoingReportEvent::DkimRateLimited),
+                SpanId = self.data.session_id,
+                To = rcpt.to_string(),
+                Limit = vec![
+                    trc::Value::from(rate.count),
+                    trc::Value::from(rate.period.into_inner())
+                ],
+            );
+
+            return;
+        }
+
+        let config = &self.server.core.smtp.report.dkim;
+        let from_addr = self
+            .server
+            .eval_if(&config.address, self, self.data.session_id)
+            .await
+            .unwrap_or_else(|| "MAILER-DAEMON@localhost".to_string());
+        let mut report = Vec::with_capacity(128);
+        self.new_auth_failure(output.result().into(), rejected)
+            .with_authentication_results(
+                AuthenticationResults::new(&self.hostname)
+                    .with_dkim_result(output, message.from())
+                    .to_string(),
+            )
+            .with_dkim_domain(signature.domain())
+            .with_dkim_selector(signature.selector())
+            .with_dkim_identity(signature.identity())
+            .with_headers(std::str::from_utf8(message.raw_headers()).unwrap_or_default())
+            .write_rfc5322(
+                (
+                    self.server
+                        .eval_if(&config.name, self, self.data.session_id)
+                        .await
+                        .unwrap_or_else(|| "Mail Delivery Subsystem".to_string())
+                        .as_str(),
+                    from_addr.as_str(),
+                ),
+                rcpt,
+                &self
+                    .server
+                    .eval_if(&config.subject, self, self.data.session_id)
+                    .await
+                    .unwrap_or_else(|| "DKIM Report".to_string()),
+                &mut report,
+            )
+            .ok();
+
+        trc::event!(
+            OutgoingReport(OutgoingReportEvent::DkimReport),
+            SpanId = self.data.session_id,
+            From = from_addr.to_string(),
+            To = rcpt.to_string(),
+        );
+
+        // Send report
+        self.server
+            .send_report(
+                &from_addr,
+                [rcpt].into_iter(),
+                report,
+                &config.sign,
+                true,
+                self.data.session_id,
+            )
+            .await;
+    }
+}

crates/smtp/src/reporting/dmarc.rs

@@ -0,0 +1,695 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use super::AggregateTimestamp;
+use crate::{
+    core::Session,
+    queue::RecipientDomain,
+    reporting::{index::InternalReportIndex, send::MtaReportSend},
+};
+use common::{
+    Server,
+    config::smtp::report::AggregateFrequency,
+    ipc::{DmarcEvent, ToHash},
+    network::SessionStream,
+};
+use compact_str::ToCompactString;
+use mail_auth::{
+    ArcOutput, AuthenticatedMessage, AuthenticationResults, DkimOutput, DkimResult, DmarcOutput,
+    DmarcResult, SpfResult,
+    common::verify::VerifySignature,
+    dkim2::Dkim2Output,
+    dmarc::{self},
+    report::{AuthFailureType, IdentityAlignment, PolicyPublished, Record, SPFDomainScope},
+};
+use registry::{
+    schema::{
+        enums::FailureReportingOption,
+        prelude::{ObjectType, Property},
+        structs::{DmarcInternalReport, DmarcReport, DmarcReportRecord, Rate},
+    },
+    types::{EnumImpl, ObjectImpl, datetime::UTCDateTime, map::Map},
+};
+use std::{borrow::Cow, future::Future};
+use store::{
+    SerializeInfallible, U64_LEN, ValueKey,
+    registry::ObjectIdVersioned,
+    write::{BatchBuilder, RegistryClass, ValueClass, assert::AssertValue, key::KeySerializer},
+};
+use trc::{AddContext, OutgoingReportEvent};
+use utils::DomainPart;
+
+impl<T: SessionStream> Session<T> {
+    #[allow(clippy::too_many_arguments)]
+    pub async fn send_dmarc_report(
+        &self,
+        message: &AuthenticatedMessage<'_>,
+        auth_results: &AuthenticationResults<'_>,
+        rejected: bool,
+        dmarc_output: DmarcOutput,
+        dkim_output: &[DkimOutput<'_>],
+        dkim2_output: Option<&Dkim2Output<'_>>,
+        arc_output: &Option<ArcOutput<'_>>,
+    ) {
+        let dmarc_record = dmarc_output.dmarc_record_cloned().unwrap();
+        let config = &self.server.core.smtp.report.dmarc;
+
+        if self
+            .server
+            .is_local_report_domain(dmarc_output.domain(), self.data.session_id)
+            .await
+        {
+            return;
+        }
+
+        // Send failure report. RFC 9991 Section 2: report generators MUST NOT
+        // honor "ruf" for policy records published with "psd=y".
+        if !matches!(dmarc_record.psd, dmarc::Psd::Yes)
+            && let (Some(failure_rate), Some(report_options)) = (
+                self.server
+                    .eval_if::<Rate, _>(&config.send, self, self.data.session_id)
+                    .await,
+                dmarc_output.failure_report(),
+            )
+        {
+            // Verify that any external reporting addresses are authorized
+            let rcpts = match self
+                .server
+                .core
+                .smtp
+                .resolvers
+                .dns
+                .verify_dmarc_report_address(
+                    dmarc_output.domain(),
+                    dmarc_record.ruf(),
+                    Some(&self.server.inner.cache.dns_txt),
+                )
+                .await
+            {
+                Some(rcpts) => {
+                    if !rcpts.is_empty() {
+                        let mut new_rcpts = Vec::with_capacity(rcpts.len());
+
+                        for rcpt in rcpts {
+                            if self.throttle_rcpt(rcpt.uri(), &failure_rate, "dmarc").await {
+                                new_rcpts.push(rcpt.uri());
+                            }
+                        }
+
+                        new_rcpts
+                    } else {
+                        if !dmarc_record.ruf().is_empty() {
+                            trc::event!(
+                                OutgoingReport(OutgoingReportEvent::UnauthorizedReportingAddress),
+                                SpanId = self.data.session_id,
+                                Url = dmarc_record
+                                    .ruf()
+                                    .iter()
+                                    .map(|u| trc::Value::String(u.uri().to_compact_string()))
+                                    .collect::<Vec<_>>(),
+                            );
+                        }
+                        vec![]
+                    }
+                }
+                None => {
+                    trc::event!(
+                        OutgoingReport(OutgoingReportEvent::ReportingAddressValidationError),
+                        SpanId = self.data.session_id,
+                        Url = dmarc_record
+                            .ruf()
+                            .iter()
+                            .map(|u| trc::Value::String(u.uri().to_compact_string()))
+                            .collect::<Vec<_>>(),
+                    );
+
+                    vec![]
+                }
+            };
+
+            // Throttle recipient
+            if !rcpts.is_empty() {
+                let mut report = Vec::with_capacity(128);
+                let from_addr = self
+                    .server
+                    .eval_if(&config.address, self, self.data.session_id)
+                    .await
+                    .unwrap_or_else(|| "MAILER-DAEMON@localhost".to_compact_string());
+                let mut auth_failure = self
+                    .new_auth_failure(AuthFailureType::Dmarc, rejected)
+                    .with_authentication_results(auth_results.to_string())
+                    .with_headers(std::str::from_utf8(message.raw_headers()).unwrap_or_default());
+
+                let dkim_aligned = matches!(dmarc_output.dkim_result(), DmarcResult::Pass);
+                let spf_aligned = matches!(dmarc_output.spf_result(), DmarcResult::Pass);
+
+                // Report the first failed signature
+                if let (
+                    dmarc::Report::Dkim
+                    | dmarc::Report::DkimSpf
+                    | dmarc::Report::All
+                    | dmarc::Report::Any,
+                    Some(signature),
+                ) = (
+                    &report_options,
+                    if !dkim_aligned {
+                        dkim_output
+                            .iter()
+                            .find_map(|o| {
+                                let s = o.signature()?;
+                                if !matches!(o.result(), DkimResult::Pass) {
+                                    Some(s)
+                                } else {
+                                    None
+                                }
+                            })
+                            .or_else(|| dkim_output.iter().find_map(|o| o.signature()))
+                    } else {
+                        None
+                    },
+                ) {
+                    auth_failure = auth_failure
+                        .with_dkim_domain(signature.domain())
+                        .with_dkim_selector(signature.selector())
+                        .with_dkim_identity(signature.identity());
+                }
+
+                // Report SPF failure
+                if let (
+                    dmarc::Report::Spf
+                    | dmarc::Report::DkimSpf
+                    | dmarc::Report::All
+                    | dmarc::Report::Any,
+                    Some(output),
+                ) = (
+                    &report_options,
+                    if !spf_aligned {
+                        self.data
+                            .spf_ehlo
+                            .as_ref()
+                            .and_then(|s| {
+                                if s.result() != SpfResult::Pass {
+                                    s.into()
+                                } else {
+                                    None
+                                }
+                            })
+                            .or_else(|| {
+                                self.data.spf_mail_from.as_ref().and_then(|s| {
+                                    if s.result() != SpfResult::Pass {
+                                        s.into()
+                                    } else {
+                                        None
+                                    }
+                                })
+                            })
+                            .or(self.data.spf_mail_from.as_ref())
+                    } else {
+                        None
+                    },
+                ) {
+                    auth_failure =
+                        auth_failure.with_spf_dns(format!("txt : {} : v=SPF1", output.domain()));
+                    // TODO use DNS record
+                }
+
+                auth_failure
+                    .with_identity_alignment(match (dkim_aligned, spf_aligned) {
+                        (false, false) => IdentityAlignment::DkimSpf,
+                        (false, true) => IdentityAlignment::Dkim,
+                        (true, false) => IdentityAlignment::Spf,
+                        (true, true) => IdentityAlignment::None,
+                    })
+                    .write_rfc5322(
+                        (
+                            self.server
+                                .eval_if(&config.name, self, self.data.session_id)
+                                .await
+                                .unwrap_or_else(|| "Mail Delivery Subsystem".to_compact_string())
+                                .as_str(),
+                            from_addr.as_str(),
+                        ),
+                        &rcpts.join(", "),
+                        &self
+                            .server
+                            .eval_if(&config.subject, self, self.data.session_id)
+                            .await
+                            .unwrap_or_else(|| "DMARC Report".to_compact_string()),
+                        &mut report,
+                    )
+                    .ok();
+
+                trc::event!(
+                    OutgoingReport(OutgoingReportEvent::DmarcReport),
+                    SpanId = self.data.session_id,
+                    From = from_addr.to_string(),
+                    To = rcpts
+                        .iter()
+                        .map(|a| trc::Value::String(a.to_compact_string()))
+                        .collect::<Vec<_>>(),
+                );
+
+                // Send report
+                self.server
+                    .send_report(
+                        &from_addr,
+                        rcpts.into_iter(),
+                        report,
+                        &config.sign,
+                        true,
+                        self.data.session_id,
+                    )
+                    .await;
+            } else {
+                trc::event!(
+                    OutgoingReport(OutgoingReportEvent::DmarcRateLimited),
+                    SpanId = self.data.session_id,
+                    Limit = vec![
+                        trc::Value::from(failure_rate.count),
+                        trc::Value::from(failure_rate.period.into_inner())
+                    ],
+                );
+            }
+        }
+
+        // Send aggregate reports
+        let interval = self
+            .server
+            .eval_if(
+                &self.server.core.smtp.report.dmarc_aggregate.send,
+                self,
+                self.data.session_id,
+            )
+            .await
+            .unwrap_or(AggregateFrequency::Never);
+
+        if matches!(interval, AggregateFrequency::Never) || dmarc_record.rua().is_empty() {
+            return;
+        }
+
+        // Report the same identifier forms that were used for alignment
+        let message_from = message.from();
+        let header_from = message_from.domain_part();
+        let header_from = header_from
+            .to_ascii_domain()
+            .unwrap_or(Cow::Borrowed(header_from));
+        let envelope_from = self
+            .data
+            .mail_from
+            .as_ref()
+            .map(|mf| mf.domain.as_str())
+            .unwrap_or_else(|| self.data.helo_domain.as_str());
+        let envelope_from = envelope_from
+            .to_ascii_domain()
+            .unwrap_or(Cow::Borrowed(envelope_from));
+
+        // Create DMARC report record
+        let mut report_record = Record::new()
+            .with_dmarc_output(&dmarc_output)
+            .with_dkim_output(dkim_output)
+            .with_source_ip(self.data.remote_ip)
+            .with_header_from(header_from.as_ref())
+            .with_envelope_from(envelope_from.as_ref());
+        if let Some(dkim2_output) = dkim2_output {
+            report_record = report_record.with_dkim2_output(dkim2_output);
+        }
+        if let Some(spf_ehlo) = &self.data.spf_ehlo {
+            report_record = report_record.with_spf_output(spf_ehlo, SPFDomainScope::Helo);
+        }
+        if let Some(spf_mail_from) = &self.data.spf_mail_from {
+            report_record = report_record.with_spf_output(spf_mail_from, SPFDomainScope::MailFrom);
+        }
+        if let Some(arc_output) = arc_output {
+            report_record = report_record.with_arc_output(arc_output);
+        }
+
+        // Submit DMARC report event
+        self.server
+            .schedule_report(DmarcEvent {
+                domain: dmarc_output.into_domain(),
+                report_record,
+                dmarc_record,
+                interval,
+                span_id: self.data.session_id,
+            })
+            .await;
+    }
+}
+
+pub trait DmarcReporting: Sync + Send {
+    fn send_dmarc_aggregate_report(
+        &self,
+        report_id: u64,
+    ) -> impl Future<Output = trc::Result<()>> + Send;
+    fn schedule_dmarc(&self, event: Box<DmarcEvent>) -> impl Future<Output = ()> + Send;
+}
+
+impl DmarcReporting for Server {
+    async fn send_dmarc_aggregate_report(&self, item_id: u64) -> trc::Result<()> {
+        let object_id = ObjectType::DmarcInternalReport.to_id();
+        let key = ValueClass::Registry(RegistryClass::Item { object_id, item_id });
+
+        let Some(report) = self
+            .store()
+            .get_value::<DmarcInternalReport>(ValueKey::from(key.clone()))
+            .await
+            .caused_by(trc::location!())?
+        else {
+            return Ok(());
+        };
+
+        // Delete report
+        let mut batch = BatchBuilder::new();
+        batch.clear(key).clear(RegistryClass::PrimaryKey {
+            object_id: object_id.into(),
+            index_id: Property::Domain.to_id(),
+            key: KeySerializer::new(report.domain.len() + U64_LEN)
+                .write(&report.domain)
+                .write(report.policy_identifier)
+                .finalize(),
+        });
+        self.store()
+            .write(batch.build_all())
+            .await
+            .caused_by(trc::location!())?;
+
+        let span_id = self.inner.data.span_id_gen.generate();
+        let event_from = report.report.date_range_begin.timestamp() as u64;
+        let event_to = report.report.date_range_end.timestamp() as u64;
+
+        trc::event!(
+            OutgoingReport(OutgoingReportEvent::DmarcAggregateReport),
+            SpanId = span_id,
+            ReportId = event_from,
+            Domain = report.domain.clone(),
+            RangeFrom = trc::Value::Timestamp(event_from),
+            RangeTo = trc::Value::Timestamp(event_to),
+        );
+
+        // Verify external reporting addresses
+        let rua = match self
+            .core
+            .smtp
+            .resolvers
+            .dns
+            .verify_dmarc_report_address(
+                &report.domain,
+                report.rua.as_slice(),
+                Some(&self.inner.cache.dns_txt),
+            )
+            .await
+        {
+            Some(rcpts) => {
+                if !rcpts.is_empty() {
+                    rcpts
+                } else {
+                    trc::event!(
+                        OutgoingReport(OutgoingReportEvent::UnauthorizedReportingAddress),
+                        SpanId = span_id,
+                        Url = report
+                            .rua
+                            .into_iter()
+                            .map(|u| trc::Value::String(u.into()))
+                            .collect::<Vec<_>>(),
+                    );
+
+                    return Ok(());
+                }
+            }
+            None => {
+                trc::event!(
+                    OutgoingReport(OutgoingReportEvent::ReportingAddressValidationError),
+                    SpanId = span_id,
+                    Url = report
+                        .rua
+                        .into_iter()
+                        .map(|u| trc::Value::String(u.into()))
+                        .collect::<Vec<_>>(),
+                );
+
+                return Ok(());
+            }
+        };
+
+        // Serialize report
+        let config = &self.core.smtp.report.dmarc_aggregate;
+        let from_addr = self
+            .eval_if(
+                &config.address,
+                &RecipientDomain::new(report.domain.as_str()),
+                span_id,
+            )
+            .await
+            .unwrap_or_else(|| "MAILER-DAEMON@localhost".to_compact_string());
+        let mut message = Vec::with_capacity(2048);
+        let _ = mail_auth::report::Report::from(report.report).write_rfc5322(
+            &self
+                .eval_if(
+                    &self.core.smtp.report.submitter,
+                    &RecipientDomain::new(report.domain.as_str()),
+                    span_id,
+                )
+                .await
+                .unwrap_or_else(|| "localhost".to_compact_string()),
+            (
+                self.eval_if(
+                    &config.name,
+                    &RecipientDomain::new(report.domain.as_str()),
+                    span_id,
+                )
+                .await
+                .unwrap_or_else(|| "Mail Delivery Subsystem".to_compact_string())
+                .as_str(),
+                from_addr.as_str(),
+            ),
+            rua.iter().map(|a| a.as_str()),
+            &mut message,
+        );
+
+        // Send report
+        self.send_report(
+            &from_addr,
+            rua.iter(),
+            message,
+            &config.sign,
+            false,
+            span_id,
+        )
+        .await;
+
+        Ok(())
+    }
+
+    async fn schedule_dmarc(&self, event: Box<DmarcEvent>) {
+        let object_id = ObjectType::DmarcInternalReport.to_id();
+        let policy_hash = event.dmarc_record.to_hash();
+        let pk = ValueClass::Registry(RegistryClass::PrimaryKey {
+            object_id: object_id.into(),
+            index_id: Property::Domain.to_id(),
+            key: KeySerializer::new(event.domain.len() + U64_LEN)
+                .write(&event.domain)
+                .write(policy_hash)
+                .finalize(),
+        });
+        let mut rety_count = 0;
+
+        loop {
+            // Find the report by domain name
+            let mut batch = BatchBuilder::new();
+            let report = match self
+                .store()
+                .get_value::<ObjectIdVersioned>(ValueKey::from(pk.clone()))
+                .await
+            {
+                Ok(Some(object_id_v)) => {
+                    match self
+                        .store()
+                        .get_value::<DmarcInternalReport>(ValueKey::from(ValueClass::Registry(
+                            RegistryClass::Item {
+                                object_id,
+                                item_id: object_id_v.object_id.id().id(),
+                            },
+                        )))
+                        .await
+                    {
+                        Ok(Some(report)) => Some((object_id_v, report)),
+                        Ok(None) => {
+                            trc::event!(
+                                OutgoingReport(OutgoingReportEvent::NotFound),
+                                Id = object_id_v.object_id.id().id(),
+                                CausedBy = trc::location!(),
+                                Details = "Failed to find DMARC report for domain"
+                            );
+
+                            return;
+                        }
+                        Err(err) => {
+                            trc::error!(
+                                err.caused_by(trc::location!())
+                                    .details("Failed to query registry for DMARC report")
+                            );
+                            return;
+                        }
+                    }
+                }
+                Ok(None) => None,
+                Err(err) => {
+                    trc::error!(
+                        err.caused_by(trc::location!())
+                            .details("Failed to query registry for DMARC report")
+                    );
+                    return;
+                }
+            };
+
+            // Create report if missing
+            let config = &self.core.smtp.report.dmarc_aggregate;
+            let (item_id, mut report) = if let Some((mut object_id_v, report)) = report {
+                batch.assert_value(pk.clone(), AssertValue::U32(object_id_v.version));
+                object_id_v.version += 1;
+                batch.set(pk.clone(), object_id_v.serialize());
+
+                (object_id_v.object_id.id().id(), report)
+            } else {
+                let item_id = self.inner.data.queue_id_gen.generate();
+                let date_range_begin = UTCDateTime::now();
+                let date_range_end = UTCDateTime::from_timestamp(
+                    date_range_begin.timestamp() + event.interval.as_secs() as i64,
+                );
+                let policy =
+                    PolicyPublished::from_record(event.domain.clone(), &event.dmarc_record);
+
+                let report = DmarcInternalReport {
+                    created_at: date_range_begin,
+                    deliver_at: date_range_end,
+                    domain: event.domain.clone(),
+                    report: DmarcReport {
+                        report_id: format!("{}_{policy_hash}", date_range_begin.timestamp()),
+                        date_range_begin,
+                        date_range_end,
+                        email: self
+                            .eval_if(
+                                &config.address,
+                                &RecipientDomain::new(event.domain.as_str()),
+                                event.span_id,
+                            )
+                            .await
+                            .unwrap_or_else(|| "MAILER-DAEMON@localhost".to_string()),
+                        extra_contact_info: self
+                            .eval_if::<String, _>(
+                                &config.contact_info,
+                                &RecipientDomain::new(event.domain.as_str()),
+                                event.span_id,
+                            )
+                            .await,
+                        org_name: self
+                            .eval_if::<String, _>(
+                                &config.org_name,
+                                &RecipientDomain::new(event.domain.as_str()),
+                                event.span_id,
+                            )
+                            .await
+                            .unwrap_or_default(),
+                        policy_adkim: policy.adkim.into(),
+                        policy_aspf: policy.aspf.into(),
+                        policy_disposition: policy.p.into(),
+                        policy_domain: policy.domain,
+                        policy_failure_reporting_options: match event.dmarc_record.fo {
+                            dmarc::Report::All => vec![FailureReportingOption::All],
+                            dmarc::Report::Any => vec![FailureReportingOption::Any],
+                            dmarc::Report::Dkim => vec![FailureReportingOption::DkimFailure],
+                            dmarc::Report::Spf => vec![FailureReportingOption::SpfFailure],
+                            dmarc::Report::DkimSpf => vec![
+                                FailureReportingOption::DkimFailure,
+                                FailureReportingOption::SpfFailure,
+                            ],
+                        }
+                        .into(),
+                        policy_subdomain_disposition: policy.sp.into(),
+                        policy_np: policy.np.into(),
+                        policy_discovery_method: policy.discovery_method.into(),
+                        policy_testing_mode: policy.testing,
+                        policy_version: None,
+                        version: 1.0.into(),
+                        ..Default::default()
+                    },
+                    policy_identifier: policy_hash,
+                    rua: Map::new(
+                        event
+                            .dmarc_record
+                            .rua()
+                            .iter()
+                            .map(|u| u.uri.clone())
+                            .collect(),
+                    ),
+                };
+
+                report.write_ops(&mut batch, item_id, true);
+
+                (item_id, report)
+            };
+
+            // Add record
+            let mut record = DmarcReportRecord::from(event.report_record.clone());
+            if let Some(idx) = report
+                .report
+                .records
+                .0
+                .inner
+                .iter()
+                .position(|d| d.value.eq_except_count(&record))
+            {
+                report.report.records.0.inner[idx].value.count += 1;
+            } else {
+                record.count = 1;
+                report.report.records.push(record);
+            }
+
+            // Write entry
+            let report_bytes = report.to_pickled_vec();
+            let max_report_size = self
+                .eval_if(
+                    &config.max_size,
+                    &RecipientDomain::new(&event.domain),
+                    event.span_id,
+                )
+                .await
+                .unwrap_or(5 * 1024 * 1024);
+            if max_report_size != 0 && report_bytes.len() > max_report_size {
+                trc::event!(
+                    OutgoingReport(OutgoingReportEvent::MaxSizeExceeded),
+                    SpanId = event.span_id,
+                    Domain = event.domain.clone(),
+                    Details = report_bytes.len(),
+                    Limit = max_report_size,
+                );
+                return;
+            }
+
+            batch.set(
+                ValueClass::Registry(RegistryClass::Item { object_id, item_id }),
+                report_bytes,
+            );
+
+            match self.core.storage.data.write(batch.build_all()).await {
+                Ok(_) => {
+                    break;
+                }
+                Err(err) => {
+                    if err.is_assertion_failure() && rety_count < 3 {
+                        rety_count += 1;
+                        continue;
+                    }
+                    trc::error!(
+                        err.caused_by(trc::location!())
+                            .details("Failed to write DMARC report")
+                    );
+                    break;
+                }
+            }
+        }
+    }
+}

crates/smtp/src/reporting/inbound.rs

@@ -0,0 +1,208 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use crate::core::Session;
+use ahash::AHashMap;
+use common::USER_AGENT;
+use mail_auth::report::{
+    ActionDisposition, AuthFailureType, DeliveryResult, DmarcResult, Feedback, FeedbackType,
+    Report, tlsrpt::TlsReport,
+};
+use std::{collections::hash_map::Entry, time::SystemTime};
+use store::write::now;
+use tokio::io::{AsyncRead, AsyncWrite};
+use trc::IncomingReportEvent;
+
+impl<T: AsyncWrite + AsyncRead + Unpin> Session<T> {
+    pub fn new_auth_failure(&self, ft: AuthFailureType, rejected: bool) -> Feedback<'_> {
+        Feedback::new(FeedbackType::AuthFailure)
+            .with_auth_failure(ft)
+            .with_arrival_date(
+                SystemTime::now()
+                    .duration_since(SystemTime::UNIX_EPOCH)
+                    .map_or(0, |d| d.as_secs()) as i64,
+            )
+            .with_source_ip(self.data.remote_ip)
+            .with_reporting_mta(&self.hostname)
+            .with_user_agent(USER_AGENT)
+            .with_delivery_result(if rejected {
+                DeliveryResult::Reject
+            } else {
+                DeliveryResult::Unspecified
+            })
+    }
+
+    pub fn is_report(&self) -> bool {
+        let analysis = &self.server.core.smtp.report.analysis;
+
+        self.data
+            .rcpt_to
+            .iter()
+            .any(|addr| analysis.is_report_address(addr.report_address()))
+    }
+}
+
+pub(crate) trait LogReport {
+    fn log(&self);
+}
+
+impl LogReport for Report {
+    fn log(&self) {
+        let mut dmarc_pass = 0;
+        let mut dmarc_quarantine = 0;
+        let mut dmarc_reject = 0;
+        let mut dmarc_none = 0;
+        let mut dkim_pass = 0;
+        let mut dkim_fail = 0;
+        let mut dkim_none = 0;
+        let mut spf_pass = 0;
+        let mut spf_fail = 0;
+        let mut spf_none = 0;
+
+        for record in self.records() {
+            let count = std::cmp::min(record.count(), 1);
+
+            match record.action_disposition() {
+                ActionDisposition::Pass => {
+                    dmarc_pass += count;
+                }
+                ActionDisposition::Quarantine => {
+                    dmarc_quarantine += count;
+                }
+                ActionDisposition::Reject => {
+                    dmarc_reject += count;
+                }
+                ActionDisposition::None | ActionDisposition::Unspecified => {
+                    dmarc_none += count;
+                }
+            }
+            match record.dmarc_dkim_result() {
+                DmarcResult::Pass => {
+                    dkim_pass += count;
+                }
+                DmarcResult::Fail => {
+                    dkim_fail += count;
+                }
+                DmarcResult::Unspecified => {
+                    dkim_none += count;
+                }
+            }
+            match record.dmarc_spf_result() {
+                DmarcResult::Pass => {
+                    spf_pass += count;
+                }
+                DmarcResult::Fail => {
+                    spf_fail += count;
+                }
+                DmarcResult::Unspecified => {
+                    spf_none += count;
+                }
+            }
+        }
+
+        trc::event!(
+            IncomingReport(
+                if (dmarc_reject + dmarc_quarantine + dkim_fail + spf_fail) > 0 {
+                    IncomingReportEvent::DmarcReportWithWarnings
+                } else {
+                    IncomingReportEvent::DmarcReport
+                }
+            ),
+            RangeFrom = trc::Value::Timestamp(self.date_range_begin()),
+            RangeTo = trc::Value::Timestamp(self.date_range_end()),
+            Domain = self.domain().to_string(),
+            From = self.email().to_string(),
+            Id = self.report_id().to_string(),
+            DmarcPass = dmarc_pass,
+            DmarcQuarantine = dmarc_quarantine,
+            DmarcReject = dmarc_reject,
+            DmarcNone = dmarc_none,
+            DkimPass = dkim_pass,
+            DkimFail = dkim_fail,
+            DkimNone = dkim_none,
+            SpfPass = spf_pass,
+            SpfFail = spf_fail,
+            SpfNone = spf_none,
+        );
+    }
+}
+
+impl LogReport for TlsReport {
+    fn log(&self) {
+        for policy in self.policies.iter().take(5) {
+            let mut details = AHashMap::with_capacity(policy.failure_details.len());
+            for failure in &policy.failure_details {
+                let num_failures = std::cmp::min(1, failure.failed_session_count);
+                match details.entry(failure.result_type) {
+                    Entry::Occupied(mut e) => {
+                        *e.get_mut() += num_failures;
+                    }
+                    Entry::Vacant(e) => {
+                        e.insert(num_failures);
+                    }
+                }
+            }
+
+            trc::event!(
+                IncomingReport(if policy.summary.total_failure > 0 {
+                    IncomingReportEvent::TlsReportWithWarnings
+                } else {
+                    IncomingReportEvent::TlsReport
+                }),
+                RangeFrom =
+                    trc::Value::Timestamp(self.date_range.start_datetime.to_timestamp() as u64),
+                RangeTo = trc::Value::Timestamp(self.date_range.end_datetime.to_timestamp() as u64),
+                Domain = policy.policy.policy_domain.clone(),
+                From = self.contact_info.as_deref().unwrap_or_default().to_string(),
+                Id = self.report_id.clone(),
+                Policy = format!("{:?}", policy.policy.policy_type),
+                TotalSuccesses = policy.summary.total_success,
+                TotalFailures = policy.summary.total_failure,
+                Details = format!("{details:?}"),
+            );
+        }
+    }
+}
+
+impl LogReport for Feedback<'_> {
+    fn log(&self) {
+        trc::event!(
+            IncomingReport(match self.feedback_type() {
+                mail_auth::report::FeedbackType::Abuse => IncomingReportEvent::AbuseReport,
+                mail_auth::report::FeedbackType::AuthFailure =>
+                    IncomingReportEvent::AuthFailureReport,
+                mail_auth::report::FeedbackType::Fraud => IncomingReportEvent::FraudReport,
+                mail_auth::report::FeedbackType::NotSpam => IncomingReportEvent::NotSpamReport,
+                mail_auth::report::FeedbackType::Other => IncomingReportEvent::OtherReport,
+                mail_auth::report::FeedbackType::Virus => IncomingReportEvent::VirusReport,
+            }),
+            RangeFrom = trc::Value::Timestamp(
+                self.arrival_date()
+                    .map(|d| d as u64)
+                    .unwrap_or_else(|| { now() })
+            ),
+            Domain = self
+                .reported_domain()
+                .iter()
+                .map(|d| trc::Value::String(d.as_ref().into()))
+                .collect::<Vec<_>>(),
+            Hostname = self.reporting_mta().map(|d| trc::Value::String(d.into())),
+            Url = self
+                .reported_uri()
+                .iter()
+                .map(|d| trc::Value::String(d.as_ref().into()))
+                .collect::<Vec<_>>(),
+            RemoteIp = self.source_ip(),
+            Total = self.incidents(),
+            Result = format!("{:?}", self.delivery_result()),
+            Details = self
+                .authentication_results()
+                .iter()
+                .map(|d| trc::Value::String(d.as_ref().into()))
+                .collect::<Vec<_>>(),
+        );
+    }
+}

crates/smtp/src/reporting/index.rs

@@ -0,0 +1,412 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use registry::{
+    schema::{
+        enums::DmarcActionDisposition,
+        prelude::{ObjectType, Property},
+        structs::{
+            ArfExternalReport, DmarcExternalReport, DmarcInternalReport, Task, TaskDmarcReport,
+            TaskStatus, TaskTlsReport, TlsExternalReport, TlsInternalReport,
+        },
+    },
+    types::{
+        EnumImpl, ObjectImpl,
+        datetime::UTCDateTime,
+        id::ObjectId,
+        index::{IndexBuilder, IndexValue},
+    },
+};
+use store::{
+    SerializeInfallible, U64_LEN,
+    registry::ObjectIdVersioned,
+    write::{
+        BatchBuilder, RegistryClass, TaskQueueClass, ValueClass, assert::AssertValue,
+        key::KeySerializer,
+    },
+    xxhash_rust::xxh3::Xxh3,
+};
+use types::id::Id;
+
+pub trait InternalReportIndex: ObjectImpl {
+    fn deliver_at(&self) -> UTCDateTime;
+
+    fn set_deliver_at(&mut self, at: UTCDateTime);
+
+    fn task(&self, item_id: u64) -> Task;
+
+    fn primary_key(&self) -> ValueClass;
+
+    fn reschedule_ops(
+        &mut self,
+        batch: &mut BatchBuilder,
+        item_id: u64,
+        revision: u64,
+        at: UTCDateTime,
+    ) {
+        let current_deliver_at = self.deliver_at();
+
+        if current_deliver_at != at {
+            let object = Self::OBJECT;
+            let object_id = object.to_id();
+            let key = ValueClass::Registry(RegistryClass::Item { object_id, item_id });
+
+            self.set_deliver_at(at);
+
+            batch
+                .assert_value(key.clone(), AssertValue::Hash(revision))
+                .clear(ValueClass::TaskQueue(TaskQueueClass::Due {
+                    id: item_id,
+                    due: current_deliver_at.timestamp() as u64,
+                }))
+                .set(
+                    ValueClass::TaskQueue(TaskQueueClass::Due {
+                        id: item_id,
+                        due: at.timestamp() as u64,
+                    }),
+                    object_id.serialize(),
+                )
+                .set(key, self.to_pickled_vec());
+        }
+    }
+
+    fn write_ops(&self, batch: &mut BatchBuilder, item_id: u64, is_set: bool) {
+        let object = Self::OBJECT;
+        let object_id = object.to_id();
+        let pk = self.primary_key();
+
+        if is_set {
+            batch
+                .assert_value(pk.clone(), ())
+                .set(
+                    pk,
+                    ObjectIdVersioned {
+                        object_id: ObjectId::new(object, item_id.into()),
+                        version: 0,
+                    }
+                    .serialize(),
+                )
+                .schedule_task_with_id(item_id, self.task(item_id));
+        } else {
+            batch
+                .clear(ValueClass::Registry(RegistryClass::Item {
+                    object_id,
+                    item_id,
+                }))
+                .clear(pk)
+                .clear(ValueClass::TaskQueue(TaskQueueClass::Task { id: item_id }))
+                .clear(ValueClass::TaskQueue(TaskQueueClass::Due {
+                    id: item_id,
+                    due: self.deliver_at().timestamp() as u64,
+                }));
+        }
+    }
+}
+
+pub trait ExternalReportIndex: ObjectImpl {
+    fn text(&self) -> impl Iterator<Item = &str>;
+
+    fn tenant_id(&self) -> Option<Id>;
+
+    fn expires_at(&self) -> u64;
+
+    fn domains(&self) -> impl Iterator<Item = &str>;
+
+    fn success_fail_count(&self) -> (u64, u64);
+
+    fn unique_key(&self) -> Option<[u8; 16]>;
+
+    fn write_ops(&self, batch: &mut BatchBuilder, item_id: u64, is_set: bool) {
+        let object_id = Self::OBJECT.to_id();
+        let mut index_builder = IndexBuilder::default();
+        for text in self.text() {
+            index_builder.text(Property::Text, text);
+        }
+
+        if let Some(tenant_id) = self.tenant_id() {
+            index_builder.search(Property::MemberTenantId, tenant_id.id());
+        }
+
+        let (success_count, fail_count) = self.success_fail_count();
+        index_builder.search(Property::TotalSuccessfulSessions, success_count);
+        index_builder.search(Property::TotalFailedSessions, fail_count);
+
+        index_builder.search(Property::ExpiresAt, self.expires_at());
+
+        if let Some(unique_key) = self.unique_key() {
+            index_builder.unique(Property::ReportId, IndexValue::Bytes(unique_key.to_vec()));
+        }
+
+        batch.registry_index(object_id, item_id, index_builder.keys.iter(), is_set);
+
+        let key = ValueClass::Registry(RegistryClass::Item { object_id, item_id });
+        if is_set {
+            batch.set(key, self.to_pickled_vec());
+        } else {
+            batch.clear(key);
+        }
+    }
+}
+
+impl InternalReportIndex for DmarcInternalReport {
+    fn deliver_at(&self) -> UTCDateTime {
+        self.deliver_at
+    }
+
+    fn set_deliver_at(&mut self, at: UTCDateTime) {
+        self.deliver_at = at;
+    }
+
+    fn task(&self, item_id: u64) -> Task {
+        Task::DmarcReport(TaskDmarcReport {
+            report_id: item_id.into(),
+            status: TaskStatus::at(self.deliver_at.timestamp()),
+        })
+    }
+
+    fn primary_key(&self) -> ValueClass {
+        ValueClass::Registry(RegistryClass::PrimaryKey {
+            object_id: ObjectType::DmarcInternalReport.to_id().into(),
+            index_id: Property::Domain.to_id(),
+            key: KeySerializer::new(self.domain.len() + U64_LEN)
+                .write(self.domain.as_str())
+                .write(self.policy_identifier)
+                .finalize(),
+        })
+    }
+}
+
+impl InternalReportIndex for TlsInternalReport {
+    fn deliver_at(&self) -> UTCDateTime {
+        self.deliver_at
+    }
+
+    fn set_deliver_at(&mut self, at: UTCDateTime) {
+        self.deliver_at = at;
+    }
+
+    fn task(&self, item_id: u64) -> Task {
+        Task::TlsReport(TaskTlsReport {
+            report_id: item_id.into(),
+            status: TaskStatus::at(self.deliver_at.timestamp()),
+        })
+    }
+
+    fn primary_key(&self) -> ValueClass {
+        ValueClass::Registry(RegistryClass::PrimaryKey {
+            object_id: ObjectType::TlsInternalReport.to_id().into(),
+            index_id: Property::Domain.to_id(),
+            key: self.domain.as_bytes().to_vec(),
+        })
+    }
+}
+
+impl ExternalReportIndex for ArfExternalReport {
+    fn domains(&self) -> impl Iterator<Item = &str> {
+        let report = &self.report;
+
+        report
+            .reported_domains
+            .iter()
+            .filter_map(|s| non_empty(s))
+            .chain(
+                [report.dkim_domain.as_deref()]
+                    .into_iter()
+                    .flatten()
+                    .filter_map(non_empty),
+            )
+    }
+
+    fn text(&self) -> impl Iterator<Item = &str> {
+        let report = &self.report;
+
+        report
+            .reported_domains
+            .iter()
+            .filter_map(|s| non_empty(s))
+            .chain(
+                [
+                    report.dkim_domain.as_deref(),
+                    report.reporting_mta.as_deref(),
+                    report.original_mail_from.as_deref(),
+                    report.original_rcpt_to.as_deref(),
+                ]
+                .into_iter()
+                .flatten()
+                .filter_map(non_empty),
+            )
+            .chain(non_empty(&self.from))
+    }
+
+    fn tenant_id(&self) -> Option<Id> {
+        self.member_tenant_id
+    }
+
+    fn expires_at(&self) -> u64 {
+        self.expires_at.timestamp() as u64
+    }
+
+    fn success_fail_count(&self) -> (u64, u64) {
+        (self.report.incidents, 0)
+    }
+
+    fn unique_key(&self) -> Option<[u8; 16]> {
+        None
+    }
+}
+
+impl ExternalReportIndex for DmarcExternalReport {
+    fn domains(&self) -> impl Iterator<Item = &str> {
+        let report = &self.report;
+
+        non_empty(&report.policy_domain)
+            .into_iter()
+            .filter_map(non_empty)
+    }
+
+    fn text(&self) -> impl Iterator<Item = &str> {
+        let report = &self.report;
+
+        non_empty(&report.email)
+            .into_iter()
+            .filter_map(non_empty)
+            .chain(non_empty(&report.policy_domain))
+            .chain(report.records.iter().flat_map(|r| {
+                r.envelope_to
+                    .as_deref()
+                    .into_iter()
+                    .filter_map(non_empty)
+                    .chain(non_empty(&r.envelope_from))
+                    .chain(non_empty(&r.header_from))
+                    .chain(r.dkim_results.iter().filter_map(|d| non_empty(&d.domain)))
+                    .chain(r.spf_results.iter().filter_map(|s| non_empty(&s.domain)))
+            }))
+            .chain(non_empty(&self.from))
+    }
+
+    fn tenant_id(&self) -> Option<Id> {
+        self.member_tenant_id
+    }
+
+    fn expires_at(&self) -> u64 {
+        self.expires_at.timestamp() as u64
+    }
+
+    fn success_fail_count(&self) -> (u64, u64) {
+        let mut success_count = 0;
+        let mut fail_count = 0;
+
+        for record in self.report.records.iter() {
+            if record.evaluated_disposition == DmarcActionDisposition::Pass {
+                success_count += std::cmp::min(record.count, 1);
+            } else {
+                fail_count += std::cmp::min(record.count, 1);
+            }
+        }
+
+        (success_count, fail_count)
+    }
+
+    fn unique_key(&self) -> Option<[u8; 16]> {
+        let report = &self.report;
+
+        Some(report_key(
+            [
+                report.org_name.as_str(),
+                report.policy_domain.as_str(),
+                report.report_id.as_str(),
+            ],
+            report.date_range_begin,
+            report.date_range_end,
+        ))
+    }
+}
+
+impl ExternalReportIndex for TlsExternalReport {
+    fn domains(&self) -> impl Iterator<Item = &str> {
+        let report = &self.report;
+
+        report
+            .policies
+            .iter()
+            .flat_map(|p| non_empty(&p.policy_domain).into_iter())
+    }
+
+    fn text(&self) -> impl Iterator<Item = &str> {
+        let report = &self.report;
+
+        report
+            .policies
+            .iter()
+            .flat_map(|p| {
+                non_empty(&p.policy_domain)
+                    .into_iter()
+                    .chain(p.mx_hosts.iter().filter_map(|s| non_empty(s)))
+                    .chain(p.failure_details.iter().flat_map(|fd| {
+                        non_empty_opt(&fd.receiving_mx_hostname)
+                            .into_iter()
+                            .chain(non_empty_opt(&fd.receiving_mx_helo))
+                    }))
+            })
+            .chain(non_empty(&self.from))
+    }
+
+    fn tenant_id(&self) -> Option<Id> {
+        self.member_tenant_id
+    }
+
+    fn expires_at(&self) -> u64 {
+        self.expires_at.timestamp() as u64
+    }
+
+    fn success_fail_count(&self) -> (u64, u64) {
+        let mut success_count = 0;
+        let mut fail_count = 0;
+
+        for policy in self.report.policies.iter() {
+            success_count += std::cmp::min(policy.total_successful_sessions, 1);
+            fail_count += std::cmp::min(policy.total_failed_sessions, 1);
+        }
+
+        (success_count, fail_count)
+    }
+
+    fn unique_key(&self) -> Option<[u8; 16]> {
+        let report = &self.report;
+
+        Some(report_key(
+            [
+                report.organization_name.as_deref().unwrap_or_default(),
+                report.report_id.as_str(),
+            ],
+            report.date_range_start,
+            report.date_range_end,
+        ))
+    }
+}
+
+fn report_key<const N: usize>(fields: [&str; N], from: UTCDateTime, to: UTCDateTime) -> [u8; 16] {
+    let mut hasher = Xxh3::new();
+
+    for field in fields {
+        hasher.update(field.as_bytes());
+        hasher.update(&[0u8]);
+    }
+    hasher.update(&(from.timestamp() as u64).to_be_bytes());
+    hasher.update(&(to.timestamp() as u64).to_be_bytes());
+
+    hasher.digest128().to_be_bytes()
+}
+
+#[inline(always)]
+fn non_empty(s: &str) -> Option<&str> {
+    if s.is_empty() { None } else { Some(s) }
+}
+
+#[inline(always)]
+fn non_empty_opt(s: &Option<String>) -> Option<&str> {
+    s.as_deref().filter(|s| !s.is_empty())
+}

crates/smtp/src/reporting/mod.rs

@@ -0,0 +1,73 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use common::config::smtp::report::AggregateFrequency;
+use mail_parser::DateTime;
+use std::time::SystemTime;
+
+pub mod analysis;
+pub mod dkim;
+pub mod dmarc;
+pub mod inbound;
+pub mod index;
+pub mod scheduler;
+pub mod send;
+pub mod spf;
+pub mod tls;
+
+pub trait AggregateTimestamp {
+    fn to_timestamp(&self) -> u64;
+    fn to_timestamp_(&self, dt: DateTime) -> u64;
+    fn as_secs(&self) -> u64;
+    fn due(&self) -> u64;
+}
+
+impl AggregateTimestamp for AggregateFrequency {
+    fn to_timestamp(&self) -> u64 {
+        self.to_timestamp_(DateTime::from_timestamp(
+            SystemTime::now()
+                .duration_since(SystemTime::UNIX_EPOCH)
+                .map_or(0, |d| d.as_secs()) as i64,
+        ))
+    }
+
+    fn to_timestamp_(&self, mut dt: DateTime) -> u64 {
+        (match self {
+            AggregateFrequency::Hourly => {
+                dt.minute = 0;
+                dt.second = 0;
+                dt.to_timestamp()
+            }
+            AggregateFrequency::Daily => {
+                dt.hour = 0;
+                dt.minute = 0;
+                dt.second = 0;
+                dt.to_timestamp()
+            }
+            AggregateFrequency::Weekly => {
+                let dow = dt.day_of_week();
+                dt.hour = 0;
+                dt.minute = 0;
+                dt.second = 0;
+                dt.to_timestamp() - (86400 * dow as i64)
+            }
+            AggregateFrequency::Never => dt.to_timestamp(),
+        }) as u64
+    }
+
+    fn as_secs(&self) -> u64 {
+        match self {
+            AggregateFrequency::Hourly => 3600,
+            AggregateFrequency::Daily => 86400,
+            AggregateFrequency::Weekly => 7 * 86400,
+            AggregateFrequency::Never => 0,
+        }
+    }
+
+    fn due(&self) -> u64 {
+        self.to_timestamp() + self.as_secs()
+    }
+}

crates/smtp/src/reporting/scheduler.rs

@@ -0,0 +1,29 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use super::{dmarc::DmarcReporting, tls::TlsReporting};
+use common::{BuildServer, Inner, ipc::ReportingEvent};
+use std::sync::Arc;
+use tokio::sync::mpsc;
+
+pub trait SpawnReport {
+    fn spawn(self, core: Arc<Inner>);
+}
+
+impl SpawnReport for mpsc::Receiver<ReportingEvent> {
+    fn spawn(mut self, inner: Arc<Inner>) {
+        tokio::spawn(async move {
+            while let Some(event) = self.recv().await {
+                let server = inner.build_server();
+                match event {
+                    ReportingEvent::Dmarc(event) => server.schedule_dmarc(event).await,
+                    ReportingEvent::Tls(event) => server.schedule_tls(event).await,
+                    ReportingEvent::Stop => break,
+                }
+            }
+        });
+    }
+}

crates/smtp/src/reporting/send.rs

@@ -0,0 +1,150 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use crate::{
+    inbound::dkim::DkimSign,
+    queue::{
+        MessageSource,
+        spool::{QueueParams, SmtpSpool},
+    },
+};
+use common::{Server, expr::if_block::IfBlock, ipc::ReportingEvent};
+
+pub trait MtaReportSend: Sync + Send {
+    fn is_local_report_domain(
+        &self,
+        domain: &str,
+        session_id: u64,
+    ) -> impl Future<Output = bool> + Send;
+
+    fn send_report(
+        &self,
+        from_addr: &str,
+        rcpts: impl Iterator<Item = impl AsRef<str> + Sync + Send> + Sync + Send,
+        report: Vec<u8>,
+        sign_config: &IfBlock,
+        deliver_now: bool,
+        parent_session_id: u64,
+    ) -> impl Future<Output = ()> + Send;
+
+    fn send_autogenerated(
+        &self,
+        from_addr: impl AsRef<str> + Sync + Send,
+        rcpts: impl Iterator<Item = impl AsRef<str> + Sync + Send> + Sync + Send,
+        raw_message: Vec<u8>,
+        sign_config: Option<&IfBlock>,
+        parent_session_id: u64,
+    ) -> impl Future<Output = ()> + Send;
+
+    fn schedule_report(
+        &self,
+        report: impl Into<ReportingEvent> + Sync + Send,
+    ) -> impl Future<Output = ()> + Send;
+}
+
+impl MtaReportSend for Server {
+    async fn is_local_report_domain(&self, domain: &str, session_id: u64) -> bool {
+        match self.domain(domain).await {
+            Ok(domain) => domain.is_some(),
+            Err(err) => {
+                trc::error!(
+                    err.caused_by(trc::location!())
+                        .span_id(session_id)
+                        .details("Failed to lookup local domain")
+                );
+
+                false
+            }
+        }
+    }
+
+    async fn send_report(
+        &self,
+        from_addr: &str,
+        rcpts: impl Iterator<Item = impl AsRef<str> + Sync + Send> + Sync + Send,
+        report: Vec<u8>,
+        sign_config: &IfBlock,
+        deliver_now: bool,
+        parent_session_id: u64,
+    ) {
+        // Build message
+        let mut message = self.new_message(from_addr, MessageSource::Report, parent_session_id);
+        for rcpt_ in rcpts {
+            message.add_expanded_recipient(rcpt_.as_ref(), self).await;
+        }
+
+        // Schedule delivery at a random time between now and the next 3 hours
+        if !deliver_now {
+            #[cfg(not(feature = "test_mode"))]
+            {
+                use common::config::smtp::queue::QueueExpiry;
+                use rand::RngExt;
+
+                let delivery_time = rand::rng().random_range(0u64..10800u64);
+                for rcpt in &mut message.message.recipients {
+                    rcpt.retry.due += delivery_time;
+                    rcpt.notify.due += delivery_time;
+                    if let QueueExpiry::Ttl(expires) = &mut rcpt.expires {
+                        *expires += delivery_time;
+                    }
+                }
+            }
+        }
+
+        // Queue message
+        let dkim_signers = self
+            .eval_signers(sign_config, &message.message, parent_session_id)
+            .await;
+        message
+            .queue(
+                QueueParams::new(&report, parent_session_id, self).with_dkim_signers(dkim_signers),
+            )
+            .await;
+    }
+
+    async fn send_autogenerated(
+        &self,
+        from_addr: impl AsRef<str> + Sync + Send,
+        rcpts: impl Iterator<Item = impl AsRef<str> + Sync + Send> + Sync + Send,
+        raw_message: Vec<u8>,
+        sign_config: Option<&IfBlock>,
+        parent_session_id: u64,
+    ) {
+        // Build message
+        let mut message = self.new_message(
+            from_addr.as_ref(),
+            MessageSource::Autogenerated,
+            parent_session_id,
+        );
+        for rcpt in rcpts {
+            message.add_expanded_recipient(rcpt, self).await;
+        }
+
+        // Queue message
+        let dkim_signers = if let Some(sign_config) = sign_config {
+            self.eval_signers(sign_config, &message.message, parent_session_id)
+                .await
+        } else {
+            None
+        };
+        message
+            .queue(
+                QueueParams::new(&raw_message, parent_session_id, self)
+                    .with_dkim_signers(dkim_signers),
+            )
+            .await;
+    }
+
+    async fn schedule_report(&self, report: impl Into<ReportingEvent> + Sync + Send) {
+        if self.inner.ipc.report_tx.send(report.into()).await.is_err() {
+            trc::event!(
+                Server(trc::ServerEvent::ThreadError),
+                CausedBy = trc::location!(),
+                Details = "Failed to send event to ReportScheduler"
+            );
+        }
+    }
+}

crates/smtp/src/reporting/spf.rs

@@ -0,0 +1,101 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use crate::{core::Session, reporting::send::MtaReportSend};
+use common::network::SessionStream;
+use mail_auth::{AuthenticationResults, SpfOutput, report::AuthFailureType};
+use registry::schema::structs::Rate;
+use trc::OutgoingReportEvent;
+
+impl<T: SessionStream> Session<T> {
+    pub async fn send_spf_report(
+        &self,
+        rcpt: &str,
+        rate: &Rate,
+        rejected: bool,
+        output: &SpfOutput,
+    ) {
+        // Throttle recipient
+        if !self.throttle_rcpt(rcpt, rate, "spf").await {
+            trc::event!(
+                OutgoingReport(OutgoingReportEvent::SpfRateLimited),
+                SpanId = self.data.session_id,
+                To = rcpt.to_string(),
+                Limit = vec![
+                    trc::Value::from(rate.count),
+                    trc::Value::from(rate.period.into_inner())
+                ],
+            );
+
+            return;
+        }
+
+        // Generate report
+        let config = &self.server.core.smtp.report.spf;
+        let from_addr = self
+            .server
+            .eval_if(&config.address, self, self.data.session_id)
+            .await
+            .unwrap_or_else(|| "MAILER-DAEMON@localhost".to_string());
+        let mut report = Vec::with_capacity(128);
+        self.new_auth_failure(AuthFailureType::Spf, rejected)
+            .with_authentication_results(
+                if let Some(mail_from) = &self.data.mail_from {
+                    AuthenticationResults::new(&self.hostname).with_spf_mailfrom_result(
+                        output,
+                        self.data.remote_ip,
+                        &mail_from.address,
+                        &self.data.helo_domain,
+                    )
+                } else {
+                    AuthenticationResults::new(&self.hostname).with_spf_ehlo_result(
+                        output,
+                        self.data.remote_ip,
+                        &self.data.helo_domain,
+                    )
+                }
+                .to_string(),
+            )
+            .with_spf_dns(format!("txt : {} : v=SPF1", output.domain())) // TODO use DNS record
+            .write_rfc5322(
+                (
+                    self.server
+                        .eval_if(&config.name, self, self.data.session_id)
+                        .await
+                        .unwrap_or_else(|| "Mailer Daemon".to_string())
+                        .as_str(),
+                    from_addr.as_str(),
+                ),
+                rcpt,
+                &self
+                    .server
+                    .eval_if(&config.subject, self, self.data.session_id)
+                    .await
+                    .unwrap_or_else(|| "SPF Report".to_string()),
+                &mut report,
+            )
+            .ok();
+
+        trc::event!(
+            OutgoingReport(OutgoingReportEvent::SpfReport),
+            SpanId = self.data.session_id,
+            To = rcpt.to_string(),
+            From = from_addr.to_string(),
+        );
+
+        // Send report
+        self.server
+            .send_report(
+                &from_addr,
+                [rcpt].into_iter(),
+                report,
+                &config.sign,
+                true,
+                self.data.session_id,
+            )
+            .await;
+    }
+}

crates/smtp/src/reporting/tls.rs

@@ -0,0 +1,493 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use super::AggregateTimestamp;
+use crate::{
+    queue::RecipientDomain,
+    reporting::{index::InternalReportIndex, send::MtaReportSend},
+};
+use common::{
+    Server, USER_AGENT,
+    config::smtp::{
+        report::AggregateFrequency,
+        resolver::{Mode, MxPattern, TlsaMatching},
+    },
+    ipc::{TlsEvent, ToHash},
+};
+use mail_auth::{
+    flate2::{Compression, write::GzEncoder},
+    mta_sts::{ReportUri, TlsRpt},
+    report::tlsrpt::{FailureDetails, PolicyDetails},
+};
+use registry::{
+    schema::{
+        enums::TlsPolicyType,
+        prelude::{ObjectType, Property},
+        structs::{TlsFailureDetails, TlsInternalReport, TlsReport, TlsReportPolicy},
+    },
+    types::{EnumImpl, ObjectImpl, datetime::UTCDateTime},
+};
+use reqwest::header::CONTENT_TYPE;
+use std::fmt::Write;
+use std::{future::Future, sync::Arc, time::Duration};
+use store::{
+    SerializeInfallible, ValueKey,
+    registry::ObjectIdVersioned,
+    write::{BatchBuilder, RegistryClass, ValueClass, assert::AssertValue},
+};
+use trc::{AddContext, OutgoingReportEvent};
+
+#[derive(Debug, Clone)]
+pub struct TlsRptOptions {
+    pub record: Arc<TlsRpt>,
+    pub interval: AggregateFrequency,
+}
+
+#[derive(Debug, rkyv::Serialize, rkyv::Deserialize, rkyv::Archive, serde::Serialize)]
+pub struct TlsFormat {
+    pub rua: Vec<ReportUri>,
+    pub policy: PolicyDetails,
+    pub records: Vec<Option<FailureDetails>>,
+}
+
+#[cfg(feature = "test_mode")]
+pub static TLS_HTTP_REPORT: parking_lot::Mutex<Vec<u8>> = parking_lot::Mutex::new(Vec::new());
+
+pub trait TlsReporting: Sync + Send {
+    fn send_tls_aggregate_report(
+        &self,
+        report_id: u64,
+    ) -> impl Future<Output = trc::Result<()>> + Send;
+
+    fn schedule_tls(&self, event: Box<TlsEvent>) -> impl Future<Output = ()> + Send;
+}
+
+impl TlsReporting for Server {
+    async fn send_tls_aggregate_report(&self, item_id: u64) -> trc::Result<()> {
+        let object_id = ObjectType::TlsInternalReport.to_id();
+        let key = ValueClass::Registry(RegistryClass::Item { object_id, item_id });
+
+        let Some(report) = self
+            .store()
+            .get_value::<TlsInternalReport>(ValueKey::from(key.clone()))
+            .await
+            .caused_by(trc::location!())?
+        else {
+            return Ok(());
+        };
+
+        // Delete report
+        let mut batch = BatchBuilder::new();
+        batch.clear(key).clear(RegistryClass::PrimaryKey {
+            object_id: object_id.into(),
+            index_id: Property::Domain.to_id(),
+            key: report.domain.as_bytes().to_vec(),
+        });
+        self.core
+            .storage
+            .data
+            .write(batch.build_all())
+            .await
+            .caused_by(trc::location!())?;
+
+        let domain_name = report.domain.as_str();
+        let event_from = report.report.date_range_start.timestamp() as u64;
+        let event_to = report.report.date_range_end.timestamp() as u64;
+        let span_id = self.inner.data.span_id_gen.generate();
+
+        trc::event!(
+            OutgoingReport(OutgoingReportEvent::TlsAggregate),
+            SpanId = span_id,
+            ReportId = event_from,
+            Domain = domain_name.to_string(),
+            RangeFrom = trc::Value::Timestamp(event_from),
+            RangeTo = trc::Value::Timestamp(event_to),
+        );
+
+        // Generate report
+        let exported_report = mail_auth::report::tlsrpt::TlsReport::from(report.report);
+        let json = exported_report.to_json();
+        let mut e = GzEncoder::new(Vec::with_capacity(json.len()), Compression::default());
+        let json = match std::io::Write::write_all(&mut e, json.as_bytes()).and_then(|_| e.finish())
+        {
+            Ok(report) => report,
+            Err(err) => {
+                trc::event!(
+                    OutgoingReport(OutgoingReportEvent::SubmissionError),
+                    SpanId = span_id,
+                    Reason = err.to_string(),
+                    Details = "Failed to compress report"
+                );
+
+                return Ok(());
+            }
+        };
+
+        // Try delivering report over HTTP
+        for uri in report.http_rua.as_slice() {
+            {
+                #[cfg(feature = "test_mode")]
+                if uri == "https://127.0.0.1/tls" {
+                    TLS_HTTP_REPORT.lock().extend_from_slice(&json);
+
+                    return Ok(());
+                }
+
+                match self
+                    .core
+                    .smtp
+                    .tls_report_client
+                    .post(uri)
+                    .timeout(Duration::from_secs(2 * 60))
+                    .header(reqwest::header::USER_AGENT, USER_AGENT)
+                    .header(CONTENT_TYPE, "application/tlsrpt+gzip")
+                    .body(json.to_vec())
+                    .send()
+                    .await
+                {
+                    Ok(response) => {
+                        if response.status().is_success() {
+                            trc::event!(
+                                OutgoingReport(OutgoingReportEvent::HttpSubmission),
+                                SpanId = span_id,
+                                Url = uri.to_string(),
+                                Code = response.status().as_u16(),
+                            );
+
+                            return Ok(());
+                        } else {
+                            trc::event!(
+                                OutgoingReport(OutgoingReportEvent::SubmissionError),
+                                SpanId = span_id,
+                                Url = uri.to_string(),
+                                Code = response.status().as_u16(),
+                                Details = "Invalid HTTP response"
+                            );
+                        }
+                    }
+                    Err(err) => {
+                        trc::event!(
+                            OutgoingReport(OutgoingReportEvent::SubmissionError),
+                            SpanId = span_id,
+                            Url = uri.to_string(),
+                            Reason = err.to_string(),
+                            Details = "HTTP submission error"
+                        );
+                    }
+                }
+            }
+        }
+
+        // Deliver report over SMTP
+        if !report.mail_rua.is_empty() {
+            let config = &self.core.smtp.report.tls;
+            let from_addr = self
+                .eval_if(&config.address, &RecipientDomain::new(domain_name), span_id)
+                .await
+                .unwrap_or_else(|| "MAILER-DAEMON@localhost".to_string());
+            let mut message = Vec::with_capacity(2048);
+            let _ = exported_report.write_rfc5322_from_bytes(
+                domain_name,
+                &self
+                    .eval_if(
+                        &self.core.smtp.report.submitter,
+                        &RecipientDomain::new(domain_name),
+                        span_id,
+                    )
+                    .await
+                    .unwrap_or_else(|| "localhost".to_string()),
+                (
+                    self.eval_if(&config.name, &RecipientDomain::new(domain_name), span_id)
+                        .await
+                        .unwrap_or_else(|| "Mail Delivery Subsystem".to_string())
+                        .as_str(),
+                    from_addr.as_str(),
+                ),
+                report.mail_rua.iter().map(|v| v.as_str()),
+                &json,
+                &mut message,
+            );
+
+            // Send report
+            self.send_report(
+                &from_addr,
+                report.mail_rua.iter().map(|v| v.as_str()),
+                message,
+                &config.sign,
+                false,
+                span_id,
+            )
+            .await;
+        } else {
+            trc::event!(
+                OutgoingReport(OutgoingReportEvent::NoRecipientsFound),
+                SpanId = span_id,
+            );
+        }
+
+        Ok(())
+    }
+
+    async fn schedule_tls(&self, event: Box<TlsEvent>) {
+        let object_id = ObjectType::TlsInternalReport.to_id();
+        let pk = ValueClass::Registry(RegistryClass::PrimaryKey {
+            object_id: object_id.into(),
+            index_id: Property::Domain.to_id(),
+            key: event.domain.as_bytes().to_vec(),
+        });
+        let mut rety_count = 0;
+        let policy_hash = event.policy.to_hash();
+
+        loop {
+            // Find the report by domain name
+            let mut batch = BatchBuilder::new();
+            let report = match self
+                .store()
+                .get_value::<ObjectIdVersioned>(ValueKey::from(pk.clone()))
+                .await
+            {
+                Ok(Some(object_id_v)) => {
+                    match self
+                        .store()
+                        .get_value::<TlsInternalReport>(ValueKey::from(ValueClass::Registry(
+                            RegistryClass::Item {
+                                object_id,
+                                item_id: object_id_v.object_id.id().id(),
+                            },
+                        )))
+                        .await
+                    {
+                        Ok(Some(report)) => Some((object_id_v, report)),
+                        Ok(None) => {
+                            trc::event!(
+                                OutgoingReport(OutgoingReportEvent::NotFound),
+                                Id = object_id_v.object_id.id().id(),
+                                CausedBy = trc::location!(),
+                                Details = "Failed to find TLS report for domain"
+                            );
+
+                            return;
+                        }
+                        Err(err) => {
+                            trc::error!(
+                                err.caused_by(trc::location!())
+                                    .details("Failed to query registry for TLS report")
+                            );
+                            return;
+                        }
+                    }
+                }
+                Ok(None) => None,
+                Err(err) => {
+                    trc::error!(
+                        err.caused_by(trc::location!())
+                            .details("Failed to query registry for TLS report")
+                    );
+                    return;
+                }
+            };
+
+            // Create report if missing
+            let config = &self.core.smtp.report.tls;
+            let (item_id, mut report) = if let Some((mut object_id_v, report)) = report {
+                batch.assert_value(pk.clone(), AssertValue::U32(object_id_v.version));
+                object_id_v.version += 1;
+                batch.set(pk.clone(), object_id_v.serialize());
+
+                (object_id_v.object_id.id().id(), report)
+            } else {
+                let item_id = self.inner.data.queue_id_gen.generate();
+                let date_range_start = UTCDateTime::now();
+                let date_range_end = UTCDateTime::from_timestamp(
+                    date_range_start.timestamp() + event.interval.as_secs() as i64,
+                );
+
+                let report = TlsInternalReport {
+                    created_at: date_range_start,
+                    deliver_at: date_range_end,
+                    domain: event.domain.clone(),
+                    report: TlsReport {
+                        report_id: format!("{}_{policy_hash}", date_range_start.timestamp()),
+                        organization_name: self
+                            .eval_if::<String, _>(
+                                &config.org_name,
+                                &RecipientDomain::new(&event.domain),
+                                event.span_id,
+                            )
+                            .await
+                            .clone(),
+                        contact_info: self
+                            .eval_if::<String, _>(
+                                &config.contact_info,
+                                &RecipientDomain::new(&event.domain),
+                                event.span_id,
+                            )
+                            .await
+                            .clone(),
+                        date_range_end,
+                        date_range_start,
+                        policies: Default::default(),
+                    },
+                    ..Default::default()
+                };
+
+                report.write_ops(&mut batch, item_id, true);
+
+                (item_id, report)
+            };
+
+            let policy = if let Some(policy) = report
+                .policy_identifiers
+                .as_slice()
+                .iter()
+                .position(|id| *id == policy_hash)
+                .and_then(|idx| report.report.policies.0.inner.get_mut(idx))
+            {
+                &mut policy.value
+            } else {
+                // Create policy
+                let mut policy = TlsReportPolicy {
+                    policy_type: TlsPolicyType::NoPolicyFound,
+                    policy_domain: report.domain.clone(),
+                    ..Default::default()
+                };
+
+                match &event.policy {
+                    common::ipc::PolicyType::Tlsa(tlsa) => {
+                        policy.policy_type = TlsPolicyType::Tlsa;
+                        if let Some(tlsa) = tlsa {
+                            for entry in &tlsa.entries {
+                                policy.policy_strings.push(format!(
+                                    "{} {} {} {}",
+                                    if entry.is_end_entity { 3 } else { 2 },
+                                    i32::from(entry.is_spki),
+                                    match entry.matching {
+                                        TlsaMatching::Full => 0,
+                                        TlsaMatching::Sha256 => 1,
+                                        TlsaMatching::Sha512 => 2,
+                                    },
+                                    entry.data.iter().fold(
+                                        String::with_capacity(64),
+                                        |mut s, b| {
+                                            write!(s, "{b:02X}").ok();
+                                            s
+                                        }
+                                    )
+                                ));
+                            }
+                        }
+                    }
+                    common::ipc::PolicyType::Sts(sts) => {
+                        policy.policy_type = TlsPolicyType::Sts;
+                        if let Some(sts) = sts {
+                            policy.policy_strings.push("version: STSv1".to_string());
+                            policy.policy_strings.push(format!(
+                                "mode: {}",
+                                match sts.mode {
+                                    Mode::Enforce => "enforce",
+                                    Mode::Testing => "testing",
+                                    Mode::None => "none",
+                                }
+                            ));
+                            policy
+                                .policy_strings
+                                .push(format!("max_age: {}", sts.max_age));
+                            for mx in &sts.mx {
+                                let mx = match mx {
+                                    MxPattern::Equals(mx) => mx.to_string(),
+                                    MxPattern::StartsWith(mx) => format!("*.{mx}"),
+                                };
+                                policy.policy_strings.push(format!("mx: {mx}"));
+                                policy.mx_hosts.push(mx);
+                            }
+                        }
+                    }
+                    _ => (),
+                }
+
+                for rua in &event.tls_record.rua {
+                    match rua {
+                        ReportUri::Mail(mail) => {
+                            report.mail_rua.push(mail.clone());
+                        }
+                        ReportUri::Http(uri) => {
+                            report.http_rua.push(uri.clone());
+                        }
+                    }
+                }
+
+                report.policy_identifiers.push(policy_hash);
+                report.report.policies.push(policy);
+                &mut report.report.policies.0.inner.last_mut().unwrap().value
+            };
+
+            // Add failure details
+            if let Some(mut failure) = event.failure.clone().map(TlsFailureDetails::from) {
+                if let Some(idx) = policy
+                    .failure_details
+                    .0
+                    .inner
+                    .iter()
+                    .position(|d| d.value.eq_except_count(&failure))
+                {
+                    policy.failure_details.0.inner[idx]
+                        .value
+                        .failed_session_count += 1;
+                } else {
+                    failure.failed_session_count = 1;
+                    policy.failure_details.push(failure);
+                }
+
+                policy.total_failed_sessions += 1;
+            } else {
+                policy.total_successful_sessions += 1;
+            }
+
+            // Write entry
+            let report_bytes = report.to_pickled_vec();
+            let max_report_size = self
+                .eval_if(
+                    &config.max_size,
+                    &RecipientDomain::new(&event.domain),
+                    event.span_id,
+                )
+                .await
+                .unwrap_or(5 * 1024 * 1024);
+            if max_report_size != 0 && report_bytes.len() > max_report_size {
+                trc::event!(
+                    OutgoingReport(OutgoingReportEvent::MaxSizeExceeded),
+                    SpanId = event.span_id,
+                    Domain = event.domain.clone(),
+                    Details = report_bytes.len(),
+                    Limit = max_report_size,
+                );
+                return;
+            }
+
+            batch.set(
+                ValueClass::Registry(RegistryClass::Item { object_id, item_id }),
+                report_bytes,
+            );
+
+            match self.core.storage.data.write(batch.build_all()).await {
+                Ok(_) => {
+                    break;
+                }
+                Err(err) => {
+                    if err.is_assertion_failure() && rety_count < 3 {
+                        rety_count += 1;
+                        continue;
+                    }
+                    trc::error!(
+                        err.caused_by(trc::location!())
+                            .details("Failed to write TLS report")
+                    );
+                    break;
+                }
+            }
+        }
+    }
+}

crates/smtp/src/scripts/envelope.rs

@@ -0,0 +1,125 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use sieve::Envelope;
+use smtp_proto::{
+    MAIL_BY_NOTIFY, MAIL_BY_RETURN, MAIL_BY_TRACE, MAIL_RET_FULL, MAIL_RET_HDRS, RCPT_NOTIFY_DELAY,
+    RCPT_NOTIFY_FAILURE, RCPT_NOTIFY_NEVER, RCPT_NOTIFY_SUCCESS,
+};
+use utils::DomainPart;
+
+use crate::core::{SessionAddress, SessionData};
+
+impl SessionData {
+    pub fn apply_envelope_modification(&mut self, envelope: Envelope, value: String) {
+        match envelope {
+            Envelope::From => {
+                let (address, address_lcase, domain) = if value.contains('@') {
+                    let address_lcase = value.to_lowercase();
+                    let domain = address_lcase.domain_part().into();
+                    (value, address_lcase, domain)
+                } else if value.is_empty() {
+                    (String::new(), String::new(), String::new())
+                } else {
+                    return;
+                };
+                if let Some(mail_from) = &mut self.mail_from {
+                    mail_from.address = address;
+                    mail_from.address_lcase = address_lcase;
+                    mail_from.domain = domain;
+                } else {
+                    self.mail_from = SessionAddress {
+                        address,
+                        address_lcase,
+                        domain,
+                        flags: 0,
+                        dsn_info: None,
+                    }
+                    .into();
+                }
+            }
+            Envelope::To => {
+                if value.contains('@') {
+                    let address_lcase = value.to_lowercase();
+                    let domain = address_lcase.domain_part().into();
+                    if let Some(rcpt_to) = self.rcpt_to.last_mut() {
+                        rcpt_to.address = value;
+                        rcpt_to.address_lcase = address_lcase;
+                        rcpt_to.domain = domain;
+                    } else {
+                        self.rcpt_to.push(SessionAddress {
+                            address: value,
+                            address_lcase,
+                            domain,
+                            flags: 0,
+                            dsn_info: None,
+                        });
+                    }
+                }
+            }
+            Envelope::ByMode => {
+                if let Some(mail_from) = &mut self.mail_from {
+                    mail_from.flags &= !(MAIL_BY_NOTIFY | MAIL_BY_RETURN);
+                    if value == "N" {
+                        mail_from.flags |= MAIL_BY_NOTIFY;
+                    } else if value == "R" {
+                        mail_from.flags |= MAIL_BY_RETURN;
+                    }
+                }
+            }
+            Envelope::ByTrace => {
+                if let Some(mail_from) = &mut self.mail_from {
+                    if value == "T" {
+                        mail_from.flags |= MAIL_BY_TRACE;
+                    } else {
+                        mail_from.flags &= !MAIL_BY_TRACE;
+                    }
+                }
+            }
+            Envelope::Notify => {
+                if let Some(rcpt_to) = self.rcpt_to.last_mut() {
+                    rcpt_to.flags &= !(RCPT_NOTIFY_DELAY
+                        | RCPT_NOTIFY_FAILURE
+                        | RCPT_NOTIFY_SUCCESS
+                        | RCPT_NOTIFY_NEVER);
+                    if value == "NEVER" {
+                        rcpt_to.flags |= RCPT_NOTIFY_NEVER;
+                    } else {
+                        for value in value.split(',') {
+                            match value.trim() {
+                                "SUCCESS" => rcpt_to.flags |= RCPT_NOTIFY_SUCCESS,
+                                "FAILURE" => rcpt_to.flags |= RCPT_NOTIFY_FAILURE,
+                                "DELAY" => rcpt_to.flags |= RCPT_NOTIFY_DELAY,
+                                _ => (),
+                            }
+                        }
+                    }
+                }
+            }
+            Envelope::Ret => {
+                if let Some(mail_from) = &mut self.mail_from {
+                    mail_from.flags &= !(MAIL_RET_FULL | MAIL_RET_HDRS);
+                    if value == "FULL" {
+                        mail_from.flags |= MAIL_RET_FULL;
+                    } else if value == "HDRS" {
+                        mail_from.flags |= MAIL_RET_HDRS;
+                    }
+                }
+            }
+            Envelope::Orcpt => {
+                if let Some(rcpt_to) = self.rcpt_to.last_mut() {
+                    rcpt_to.dsn_info = value.into();
+                }
+            }
+            Envelope::Envid => {
+                if let Some(mail_from) = &mut self.mail_from {
+                    mail_from.dsn_info = value.into();
+                }
+            }
+            Envelope::ByTimeAbsolute | Envelope::ByTimeRelative => (),
+        }
+    }
+}

crates/smtp/src/scripts/event_loop.rs

@@ -0,0 +1,435 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use crate::queue::{
+    MessageSource,
+    quota::HasQueueQuota,
+    spool::{QueueParams, SmtpSpool},
+};
+use common::{Server, config::smtp::queue::QueueExpiry, scripts::plugins::PluginContext};
+use mail_parser::{Encoding, Message, MessagePart, PartType};
+use sieve::{
+    Event, Input, MatchAs, Recipient, Sieve,
+    compiler::grammar::actions::action_redirect::{ByMode, ByTime, Notify, NotifyItem, Ret},
+};
+use smtp_proto::{
+    MAIL_BY_TRACE, MAIL_RET_FULL, MAIL_RET_HDRS, RCPT_NOTIFY_DELAY, RCPT_NOTIFY_FAILURE,
+    RCPT_NOTIFY_NEVER, RCPT_NOTIFY_SUCCESS,
+};
+use std::{future::Future, sync::Arc, time::Instant};
+use trc::SieveEvent;
+
+use super::{ScriptModification, ScriptParameters, ScriptResult};
+
+pub trait RunScript: Sync + Send {
+    fn run_script(
+        &self,
+        script_id: String,
+        script: Arc<Sieve>,
+        params: ScriptParameters<'_>,
+    ) -> impl Future<Output = ScriptResult> + Send;
+}
+
+impl RunScript for Server {
+    async fn run_script(
+        &self,
+        script_id: String,
+        script: Arc<Sieve>,
+        params: ScriptParameters<'_>,
+    ) -> ScriptResult {
+        // Create filter instance
+        let time = Instant::now();
+        let mut instance = self
+            .core
+            .sieve
+            .trusted_runtime
+            .filter_parsed(params.message.unwrap_or_else(|| Message {
+                parts: vec![MessagePart {
+                    headers: vec![],
+                    is_encoding_problem: false,
+                    body: PartType::Text("".into()),
+                    encoding: Encoding::None,
+                    offset_header: 0,
+                    offset_body: 0,
+                    offset_end: 0,
+                }],
+                raw_message: b""[..].into(),
+                ..Default::default()
+            }))
+            .with_vars_env(params.variables)
+            .with_envelope_list(params.envelope)
+            .with_user_address(&params.from_addr)
+            .with_user_full_name(&params.from_name);
+        if let Some(spam_status) = params.spam_status {
+            instance.set_spam_status(spam_status);
+        }
+        let mut input = Input::script("__script", script);
+        let mut messages: Vec<Vec<u8>> = Vec::new();
+        let session_id = params.session_id;
+
+        let mut reject_reason = None;
+        let mut modifications = vec![];
+        let mut keep_id = usize::MAX;
+
+        // Start event loop
+        while let Some(result) = instance.run(input) {
+            match result {
+                Ok(event) => match event {
+                    Event::IncludeScript { name, optional } => {
+                        if let Some(script) = self.core.sieve.trusted_script(name.as_str()) {
+                            input = Input::script(name, script.clone());
+                        } else if optional {
+                            input = false.into();
+                        } else {
+                            trc::event!(
+                                Sieve(SieveEvent::ScriptNotFound),
+                                Id = script_id.clone(),
+                                SpanId = session_id,
+                                Details = name.as_str().to_string(),
+                            );
+                            break;
+                        }
+                    }
+                    Event::ListContains {
+                        lists,
+                        values,
+                        match_as,
+                    } => {
+                        input = false.into();
+                        'outer: for list in lists {
+                            if let Some(store) = self.get_lookup_store(&list) {
+                                for value in &values {
+                                    if let Ok(true) = store
+                                        .key_exists(if !matches!(match_as, MatchAs::Lowercase) {
+                                            value.clone()
+                                        } else {
+                                            value.to_lowercase()
+                                        })
+                                        .await
+                                    {
+                                        input = true.into();
+                                        break 'outer;
+                                    }
+                                }
+                            } else {
+                                trc::event!(
+                                    Sieve(SieveEvent::ListNotFound),
+                                    Id = script_id.clone(),
+                                    SpanId = session_id,
+                                    Details = list,
+                                );
+                            }
+                        }
+                    }
+                    Event::Function { id, arguments } => {
+                        input = self
+                            .core
+                            .run_plugin(
+                                id,
+                                PluginContext {
+                                    session_id,
+                                    server: self,
+                                    message: instance.message(),
+                                    modifications: &mut modifications,
+                                    access_token: params.access_token,
+                                    arguments,
+                                },
+                            )
+                            .await;
+                    }
+                    Event::Keep { message_id, .. } => {
+                        keep_id = message_id;
+                        input = true.into();
+                    }
+                    Event::Discard => {
+                        keep_id = usize::MAX - 1;
+                        input = true.into();
+                    }
+                    Event::Reject { reason, .. } => {
+                        reject_reason = reason.into();
+                        input = true.into();
+                    }
+                    Event::SendMessage {
+                        recipient,
+                        notify,
+                        return_of_content,
+                        by_time,
+                        message_id,
+                    } => {
+                        // Build message
+                        let mut message = self.new_message(
+                            params.return_path.as_str(),
+                            MessageSource::Autogenerated,
+                            session_id,
+                        );
+                        match recipient {
+                            Recipient::Address(rcpt) => {
+                                message.expand_and_add_recipient(rcpt, self).await;
+                            }
+                            Recipient::Group(rcpt_list) => {
+                                for rcpt in rcpt_list {
+                                    message.expand_and_add_recipient(rcpt, self).await;
+                                }
+                            }
+                            Recipient::List(list) => {
+                                trc::event!(
+                                    Sieve(SieveEvent::NotSupported),
+                                    Id = script_id.clone(),
+                                    SpanId = session_id,
+                                    Details = list,
+                                    Reason = "Sending to lists is not supported.",
+                                );
+                            }
+                        }
+
+                        // Set notify flags
+                        let mut flags = 0;
+                        match notify {
+                            Notify::Never => {
+                                flags = RCPT_NOTIFY_NEVER;
+                            }
+                            Notify::Items(items) => {
+                                for item in items {
+                                    flags |= match item {
+                                        NotifyItem::Success => RCPT_NOTIFY_SUCCESS,
+                                        NotifyItem::Failure => RCPT_NOTIFY_FAILURE,
+                                        NotifyItem::Delay => RCPT_NOTIFY_DELAY,
+                                    };
+                                }
+                            }
+                            Notify::Default => (),
+                        }
+                        if flags > 0 {
+                            for rcpt in &mut message.message.recipients {
+                                rcpt.flags |= flags;
+                            }
+                        }
+
+                        // Set ByTime flags
+                        match by_time {
+                            ByTime::Relative {
+                                rlimit,
+                                mode,
+                                trace,
+                            } => {
+                                if trace {
+                                    message.message.flags |= MAIL_BY_TRACE;
+                                }
+                                match mode {
+                                    ByMode::Notify => {
+                                        for domain in &mut message.message.recipients {
+                                            domain.notify.due += rlimit;
+                                        }
+                                    }
+                                    ByMode::Return => {
+                                        for domain in &mut message.message.recipients {
+                                            domain.notify.due += rlimit;
+                                        }
+                                    }
+                                    ByMode::Default => (),
+                                }
+                            }
+                            ByTime::Absolute {
+                                alimit,
+                                mode,
+                                trace,
+                            } => {
+                                if trace {
+                                    message.message.flags |= MAIL_BY_TRACE;
+                                }
+                                match mode {
+                                    ByMode::Notify => {
+                                        for domain in &mut message.message.recipients {
+                                            domain.notify.due = alimit as u64;
+                                        }
+                                    }
+                                    ByMode::Return => {
+                                        let expires =
+                                            (alimit as u64).saturating_sub(message.message.created);
+                                        if expires > 0 {
+                                            for domain in &mut message.message.recipients {
+                                                domain.expires = QueueExpiry::Ttl(expires);
+                                            }
+                                        }
+                                    }
+                                    ByMode::Default => (),
+                                }
+                            }
+                            ByTime::None => (),
+                        };
+
+                        // Set ret
+                        match return_of_content {
+                            Ret::Full => {
+                                message.message.flags |= MAIL_RET_FULL;
+                            }
+                            Ret::Hdrs => {
+                                message.message.flags |= MAIL_RET_HDRS;
+                            }
+                            Ret::Default => (),
+                        }
+
+                        // Queue message
+                        let is_forward = message_id == 0;
+                        let raw_message = if !is_forward {
+                            messages.get(message_id - 1).map(|m| m.as_slice())
+                        } else {
+                            instance.message().raw_message().into()
+                        };
+                        if let Some(raw_message) = raw_message.filter(|m| !m.is_empty()) {
+                            if let Some(metadata) = self.has_quota(&mut message).await {
+                                let dkim_signers = if let Some(sign_domain) = &params.sign_domain {
+                                    match self.dkim_signers(sign_domain).await {
+                                        Ok(signers) => signers,
+                                        Err(err) => {
+                                            trc::error!(
+                                                err.details("Failed to obtain DKIM signers")
+                                                    .caused_by(trc::location!())
+                                            );
+
+                                            None
+                                        }
+                                    }
+                                } else {
+                                    None
+                                };
+
+                                message
+                                    .queue(
+                                        QueueParams::new(raw_message, session_id, self)
+                                            .with_dkim_signers(dkim_signers)
+                                            .with_raw_headers_opt(
+                                                params.headers.filter(|_| is_forward),
+                                            )
+                                            .with_original_raw_message(
+                                                instance.message().raw_message(),
+                                            )
+                                            .with_metadata(metadata),
+                                    )
+                                    .await;
+                            } else {
+                                trc::event!(
+                                    Sieve(SieveEvent::QuotaExceeded),
+                                    SpanId = session_id,
+                                    Id = script_id.clone(),
+                                    From = message.message.return_path,
+                                    To = message
+                                        .message
+                                        .recipients
+                                        .into_iter()
+                                        .map(|r| trc::Value::from(r.address().to_string()))
+                                        .collect::<Vec<_>>(),
+                                );
+                            }
+                        }
+
+                        input = true.into();
+                    }
+                    Event::CreatedMessage { message, .. } => {
+                        messages.push(message);
+                        input = true.into();
+                    }
+                    Event::SetEnvelope { envelope, value } => {
+                        modifications.push(ScriptModification::SetEnvelope {
+                            name: envelope,
+                            value,
+                        });
+                        input = true.into();
+                    }
+                    unsupported => {
+                        trc::event!(
+                            Sieve(SieveEvent::NotSupported),
+                            Id = script_id.clone(),
+                            SpanId = session_id,
+                            Reason = "Unsupported event",
+                            Details = format!("{unsupported:?}"),
+                        );
+                        break;
+                    }
+                },
+                Err(err) => {
+                    trc::event!(
+                        Sieve(SieveEvent::RuntimeError),
+                        Id = script_id.clone(),
+                        SpanId = session_id,
+                        Reason = err.to_string(),
+                    );
+                    break;
+                }
+            }
+        }
+
+        // Keep id
+        // 0 = use original message
+        // MAX = implicit keep
+        // MAX - 1 = discard message
+
+        if keep_id == 0 {
+            trc::event!(
+                Sieve(SieveEvent::ActionAccept),
+                SpanId = session_id,
+                Id = script_id,
+                Elapsed = time.elapsed(),
+            );
+
+            ScriptResult::Accept { modifications }
+        } else if let Some(mut reject_reason) = reject_reason {
+            trc::event!(
+                Sieve(SieveEvent::ActionReject),
+                Id = script_id,
+                SpanId = session_id,
+                Details = reject_reason.clone(),
+                Elapsed = time.elapsed(),
+            );
+
+            if !reject_reason.ends_with('\n') {
+                reject_reason.push_str("\r\n");
+            }
+            let mut reject_bytes = reject_reason.as_bytes().iter();
+            if matches!(reject_bytes.next(), Some(ch) if ch.is_ascii_digit())
+                && matches!(reject_bytes.next(), Some(ch) if ch.is_ascii_digit())
+                && matches!(reject_bytes.next(), Some(ch) if ch.is_ascii_digit())
+                && matches!(reject_bytes.next(), Some(ch) if ch == &b' ' )
+            {
+                ScriptResult::Reject(reject_reason)
+            } else {
+                ScriptResult::Reject(format!("503 5.5.3 {reject_reason}"))
+            }
+        } else if keep_id != usize::MAX - 1 {
+            if let Some(message) = messages.into_iter().nth(keep_id - 1) {
+                trc::event!(
+                    Sieve(SieveEvent::ActionAccept),
+                    SpanId = session_id,
+                    Id = script_id,
+                    Elapsed = time.elapsed(),
+                );
+
+                ScriptResult::Replace {
+                    message,
+                    modifications,
+                }
+            } else {
+                trc::event!(
+                    Sieve(SieveEvent::ActionAcceptReplace),
+                    SpanId = session_id,
+                    Id = script_id,
+                    Elapsed = time.elapsed(),
+                );
+
+                ScriptResult::Accept { modifications }
+            }
+        } else {
+            trc::event!(
+                Sieve(SieveEvent::ActionDiscard),
+                SpanId = session_id,
+                Id = script_id,
+                Elapsed = time.elapsed()
+            );
+
+            ScriptResult::Discard
+        }
+    }
+}

crates/smtp/src/scripts/exec.rs

@@ -0,0 +1,175 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use std::{sync::Arc, time::SystemTime};
+
+use common::network::SessionStream;
+
+use mail_auth::common::resolver::ToReverseName;
+use sieve::{Envelope, Sieve, runtime::Variable};
+use smtp_proto::*;
+
+use crate::{core::Session, inbound::AuthResult};
+
+use super::{ScriptParameters, ScriptResult, event_loop::RunScript};
+
+impl<T: SessionStream> Session<T> {
+    pub fn build_script_parameters(&self, stage: &'static str) -> ScriptParameters<'_> {
+        let (tls_version, tls_cipher) = self.stream.tls_version_and_cipher();
+        let mut params = ScriptParameters::new()
+            .set_variable("remote_ip", self.data.remote_ip.to_string())
+            .set_variable("remote_ip.reverse", self.data.remote_ip.to_reverse_name())
+            .set_variable("helo_domain", self.data.helo_domain.as_str().to_lowercase())
+            .set_variable(
+                "authenticated_as",
+                self.authenticated_as().unwrap_or_default().to_string(),
+            )
+            .set_variable(
+                "now",
+                SystemTime::now()
+                    .duration_since(SystemTime::UNIX_EPOCH)
+                    .map_or(0, |d| d.as_secs()),
+            )
+            .set_variable(
+                "asn",
+                self.data
+                    .asn_geo_data
+                    .asn
+                    .as_ref()
+                    .map(|r| r.id)
+                    .unwrap_or_default(),
+            )
+            .set_variable(
+                "country",
+                self.data
+                    .asn_geo_data
+                    .country
+                    .as_ref()
+                    .map(|r| r.as_str())
+                    .unwrap_or_default(),
+            )
+            .set_variable(
+                "spf.result",
+                self.data
+                    .spf_mail_from
+                    .as_ref()
+                    .map(|r| r.result().as_str())
+                    .unwrap_or_default(),
+            )
+            .set_variable(
+                "spf_ehlo.result",
+                self.data
+                    .spf_ehlo
+                    .as_ref()
+                    .map(|r| r.result().as_str())
+                    .unwrap_or_default(),
+            )
+            .set_variable("tls.version", tls_version)
+            .set_variable("tls.cipher", tls_cipher)
+            .set_variable("stage", stage);
+        if let Some(ip_rev) = &self.data.iprev {
+            params = params.set_variable("iprev.result", ip_rev.result().as_str());
+            if let Some(ptr) = ip_rev.ptr.as_ref().and_then(|addrs| addrs.first()) {
+                params = params.set_variable(
+                    "iprev.ptr",
+                    ptr.strip_suffix('.').unwrap_or(ptr).to_lowercase(),
+                );
+            }
+        }
+
+        if let Some(mail_from) = &self.data.mail_from {
+            params
+                .envelope
+                .push((Envelope::From, mail_from.address_lcase.to_string().into()));
+            if let Some(env_id) = &mail_from.dsn_info {
+                params
+                    .envelope
+                    .push((Envelope::Envid, env_id.as_str().to_lowercase().into()));
+            }
+
+            if stage != "data" {
+                if let Some(rcpt) = self.data.rcpt_to.last() {
+                    params
+                        .envelope
+                        .push((Envelope::To, rcpt.address_lcase.to_string().into()));
+                    if let Some(orcpt) = &rcpt.dsn_info {
+                        params
+                            .envelope
+                            .push((Envelope::Orcpt, orcpt.as_str().to_lowercase().into()));
+                    }
+                }
+            } else {
+                // Build recipients list
+                let mut recipients = Vec::with_capacity(self.data.rcpt_to.len());
+                let mut orcpts = Vec::with_capacity(self.data.rcpt_to.len());
+                let mut has_orcpts = false;
+
+                for rcpt in &self.data.rcpt_to {
+                    recipients.push(Variable::from(rcpt.address_lcase.to_string()));
+                    orcpts.push(match &rcpt.dsn_info {
+                        Some(orcpt) => {
+                            has_orcpts = true;
+                            Variable::from(orcpt.as_str().to_lowercase())
+                        }
+                        None => Variable::default(),
+                    });
+                }
+
+                params.envelope.push((Envelope::To, recipients.into()));
+                if has_orcpts {
+                    params.envelope.push((Envelope::Orcpt, orcpts.into()));
+                }
+            }
+
+            if (mail_from.flags & MAIL_RET_FULL) != 0 {
+                params.envelope.push((Envelope::Ret, "FULL".into()));
+            } else if (mail_from.flags & MAIL_RET_HDRS) != 0 {
+                params.envelope.push((Envelope::Ret, "HDRS".into()));
+            }
+            if (mail_from.flags & MAIL_BY_NOTIFY) != 0 {
+                params.envelope.push((Envelope::ByMode, "N".into()));
+            } else if (mail_from.flags & MAIL_BY_RETURN) != 0 {
+                params.envelope.push((Envelope::ByMode, "R".into()));
+            }
+
+            if (mail_from.flags & MAIL_BODY_7BIT) != 0 {
+                params = params.set_variable("param.body", "7bit");
+            } else if (mail_from.flags & MAIL_BODY_8BITMIME) != 0 {
+                params = params.set_variable("param.body", "8bitmime");
+            } else if (mail_from.flags & MAIL_BODY_BINARYMIME) != 0 {
+                params = params.set_variable("param.body", "binarymime");
+            }
+
+            if (mail_from.flags & MAIL_SMTPUTF8) != 0 {
+                params = params.set_variable("param.smtputf8", Variable::Integer(1));
+            }
+            if (mail_from.flags & MAIL_REQUIRETLS) != 0 {
+                params = params.set_variable("param.requiretls", Variable::Integer(1));
+            }
+        }
+
+        params
+    }
+
+    pub async fn run_script(
+        &self,
+        script_id: String,
+        script: Arc<Sieve>,
+        params: ScriptParameters<'_>,
+    ) -> ScriptResult {
+        Box::pin(
+            self.server.run_script(
+                script_id,
+                script,
+                params
+                    .with_session_id(self.data.session_id)
+                    .with_envelope(&self.server, self, self.data.session_id)
+                    .await,
+            ),
+        )
+        .await
+    }
+}

crates/smtp/src/scripts/mod.rs

@@ -0,0 +1,136 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+use std::borrow::Cow;
+
+use ahash::AHashMap;
+use common::{
+    Server, auth::AccessToken, expr::functions::ResolveVariable, scripts::ScriptModification,
+};
+
+use mail_parser::Message;
+use sieve::{Envelope, SpamStatus, runtime::Variable};
+
+pub mod envelope;
+pub mod event_loop;
+pub mod exec;
+
+#[derive(Debug, serde::Serialize)]
+pub enum ScriptResult {
+    Accept {
+        modifications: Vec<ScriptModification>,
+    },
+    Replace {
+        message: Vec<u8>,
+        modifications: Vec<ScriptModification>,
+    },
+    Reject(String),
+    Discard,
+}
+
+pub struct ScriptParameters<'x> {
+    message: Option<Message<'x>>,
+    headers: Option<&'x [u8]>,
+    variables: AHashMap<Cow<'static, str>, Variable>,
+    envelope: Vec<(Envelope, Variable)>,
+    from_addr: String,
+    from_name: String,
+    return_path: String,
+    sign_domain: Option<String>,
+    access_token: Option<&'x AccessToken>,
+    spam_status: Option<SpamStatus>,
+    session_id: u64,
+}
+
+impl<'x> ScriptParameters<'x> {
+    pub fn new() -> Self {
+        ScriptParameters {
+            variables: AHashMap::with_capacity(10),
+            envelope: Vec::with_capacity(6),
+            message: None,
+            headers: None,
+            from_addr: Default::default(),
+            from_name: Default::default(),
+            return_path: Default::default(),
+            sign_domain: Default::default(),
+            access_token: None,
+            spam_status: None,
+            session_id: Default::default(),
+        }
+    }
+
+    pub async fn with_envelope(
+        mut self,
+        server: &Server,
+        vars: &impl ResolveVariable,
+        session_id: u64,
+    ) -> Self {
+        for (variable, expr) in [
+            (&mut self.from_addr, &server.core.sieve.from_addr),
+            (&mut self.from_name, &server.core.sieve.from_name),
+            (&mut self.return_path, &server.core.sieve.return_path),
+        ] {
+            if let Some(value) = server.eval_if(expr, vars, session_id).await {
+                *variable = value;
+            }
+        }
+        self.sign_domain = server
+            .eval_if(&server.core.sieve.sign, vars, session_id)
+            .await;
+        self
+    }
+
+    pub fn with_message(self, message: Message<'x>) -> Self {
+        Self {
+            message: message.into(),
+            ..self
+        }
+    }
+
+    pub fn with_auth_headers(self, headers: &'x [u8]) -> Self {
+        Self {
+            headers: headers.into(),
+            ..self
+        }
+    }
+
+    pub fn with_spam_status(self, status: SpamStatus) -> Self {
+        Self {
+            spam_status: status.into(),
+            ..self
+        }
+    }
+
+    pub fn set_variable(
+        mut self,
+        name: impl Into<Cow<'static, str>>,
+        value: impl Into<Variable>,
+    ) -> Self {
+        self.variables.insert(name.into(), value.into());
+        self
+    }
+
+    pub fn set_envelope(mut self, envelope: Envelope, value: impl Into<Variable>) -> Self {
+        self.envelope.push((envelope, value.into()));
+        self
+    }
+
+    pub fn with_access_token(mut self, access_token: &'x AccessToken) -> Self {
+        self.access_token = Some(access_token);
+        self
+    }
+
+    pub fn with_session_id(mut self, session_id: u64) -> Self {
+        self.session_id = session_id;
+        self
+    }
+}
+
+impl Default for ScriptParameters<'_> {
+    fn default() -> Self {
+        Self::new()
+    }
+}