DLP and mail flow rules: inbuxa:MailRule over JMAP, and its permissions

Phase 2e of the DLP and mail flow rules spec, the API half.

- inbuxa:MailRule/get and /set under urn:inbuxa:jmap. Rules convert
  through serde, so what a client sends is the stored format. A create
  or change is validated whole (Rule::validate) and refused with the
  property at fault; id, createdBy, createdAt and updatedAt are the
  server's. Every change goes through the request layer's audit record.
- Six permissions, ids 674-679 (enum and schema labels): mail flow rules
  (sysMailRuleGet/Update), DLP rules (sysDlpPolicyGet/Update) and held
  mail (sysDlpReviewGet/Update, for phase 3). Either kind's permission
  gets through the gate; the handler shows and changes each rule only
  with its own kind's. All server-level: a tenant is refused (settled
  answer 3).
- Administrators get all six; the server-level Compliance Officer gets
  DLP rules to see and held mail to review (settled answer 4), added
  once to an existing server's officer role by the grant mechanism,
  which gains an officer audience.
- Privacy catalog entry for inbuxa:MailRule.

tests/src/system/mail_rules.rs: create, list in order, validation,
server-set properties refused, update, kind-separated permissions for
an officer, destroy, audit records.

crates/jmap-proto/src/object/inbuxa_mail_rule.rs

@@ -0,0 +1,218 @@
+/*
+ * SPDX-FileCopyrightText: 2026 Coffey Labs
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+//! `inbuxa:MailRule/get` and `/set` under `urn:inbuxa:jmap`: mail flow rules
+//! and DLP rules (dlp-and-mail-flow-rules spec, §2.2). `kind` says which,
+//! and which permissions reach it. The set call's `reason` argument, if
+//! given, goes into the audit log with the change.
+
+use crate::{
+    object::{AnyId, JmapObject, JmapObjectId},
+    request::deserialize::DeserializeArguments,
+};
+use jmap_tools::{Element, Key, Property};
+use std::{borrow::Cow, str::FromStr};
+use types::id::Id;
+
+#[derive(Debug, Clone, Default)]
+pub struct MailRule;
+
+#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub enum MailRuleProperty {
+    Id,
+    Name,
+    Description,
+    /// `dlp` or `transport`.
+    Kind,
+    Enabled,
+    /// Lower runs first.
+    Priority,
+    /// `outgoing`, `incoming` or `any`.
+    Direction,
+    Conditions,
+    Exceptions,
+    Actions,
+    StopProcessing,
+    CreatedBy,
+    CreatedAt,
+    UpdatedAt,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub enum MailRuleValue {
+    Id(Id),
+}
+
+impl Property for MailRuleProperty {
+    fn try_parse(parent: Option<&Key<'_, Self>>, value: &str) -> Option<Self> {
+        // Keys inside conditions and actions stay plain keys
+        match parent {
+            None => MailRuleProperty::parse(value),
+            Some(_) => None,
+        }
+    }
+
+    fn to_cow(&self) -> Cow<'static, str> {
+        match self {
+            MailRuleProperty::Id => "id",
+            MailRuleProperty::Name => "name",
+            MailRuleProperty::Description => "description",
+            MailRuleProperty::Kind => "kind",
+            MailRuleProperty::Enabled => "enabled",
+            MailRuleProperty::Priority => "priority",
+            MailRuleProperty::Direction => "direction",
+            MailRuleProperty::Conditions => "conditions",
+            MailRuleProperty::Exceptions => "exceptions",
+            MailRuleProperty::Actions => "actions",
+            MailRuleProperty::StopProcessing => "stopProcessing",
+            MailRuleProperty::CreatedBy => "createdBy",
+            MailRuleProperty::CreatedAt => "createdAt",
+            MailRuleProperty::UpdatedAt => "updatedAt",
+        }
+        .into()
+    }
+}
+
+impl MailRuleProperty {
+    fn parse(value: &str) -> Option<Self> {
+        hashify::tiny_map!(value.as_bytes(),
+            b"id" => MailRuleProperty::Id,
+            b"name" => MailRuleProperty::Name,
+            b"description" => MailRuleProperty::Description,
+            b"kind" => MailRuleProperty::Kind,
+            b"enabled" => MailRuleProperty::Enabled,
+            b"priority" => MailRuleProperty::Priority,
+            b"direction" => MailRuleProperty::Direction,
+            b"conditions" => MailRuleProperty::Conditions,
+            b"exceptions" => MailRuleProperty::Exceptions,
+            b"actions" => MailRuleProperty::Actions,
+            b"stopProcessing" => MailRuleProperty::StopProcessing,
+            b"createdBy" => MailRuleProperty::CreatedBy,
+            b"createdAt" => MailRuleProperty::CreatedAt,
+            b"updatedAt" => MailRuleProperty::UpdatedAt,
+        )
+    }
+}
+
+impl FromStr for MailRuleProperty {
+    type Err = ();
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        MailRuleProperty::parse(s).ok_or(())
+    }
+}
+
+impl Element for MailRuleValue {
+    type Property = MailRuleProperty;
+
+    fn try_parse<P>(key: &Key<'_, Self::Property>, value: &str) -> Option<Self> {
+        match key {
+            Key::Property(MailRuleProperty::Id) => Id::from_str(value).ok().map(MailRuleValue::Id),
+            _ => None,
+        }
+    }
+
+    fn to_cow(&self) -> Cow<'static, str> {
+        match self {
+            MailRuleValue::Id(id) => id.to_string().into(),
+        }
+    }
+}
+
+/// The set call's own argument: why, for the audit log.
+#[derive(Debug, Clone, Default)]
+pub struct MailRuleSetArguments {
+    pub reason: Option<String>,
+}
+
+impl<'de> DeserializeArguments<'de> for MailRuleSetArguments {
+    fn deserialize_argument<A>(&mut self, key: &str, map: &mut A) -> Result<(), A::Error>
+    where
+        A: serde::de::MapAccess<'de>,
+    {
+        if key == "reason" {
+            self.reason = map.next_value()?;
+        } else {
+            let _ = map.next_value::<serde::de::IgnoredAny>()?;
+        }
+        Ok(())
+    }
+}
+
+impl JmapObject for MailRule {
+    type Property = MailRuleProperty;
+
+    type Element = MailRuleValue;
+
+    type Id = Id;
+
+    type Filter = ();
+
+    type Comparator = ();
+
+    type GetArguments = ();
+
+    type SetArguments<'de> = MailRuleSetArguments;
+
+    type QueryArguments = ();
+
+    type CopyArguments = ();
+
+    type ParseArguments = ();
+
+    const ID_PROPERTY: Self::Property = MailRuleProperty::Id;
+}
+
+impl From<Id> for MailRuleValue {
+    fn from(id: Id) -> Self {
+        MailRuleValue::Id(id)
+    }
+}
+
+impl JmapObjectId for MailRuleValue {
+    fn as_id(&self) -> Option<Id> {
+        match self {
+            MailRuleValue::Id(id) => Some(*id),
+        }
+    }
+
+    fn as_any_id(&self) -> Option<AnyId> {
+        match self {
+            MailRuleValue::Id(id) => Some(AnyId::Id(*id)),
+        }
+    }
+
+    fn as_id_ref(&self) -> Option<&str> {
+        None
+    }
+
+    fn try_set_id(&mut self, new_id: AnyId) -> bool {
+        if let AnyId::Id(id) = new_id {
+            *self = MailRuleValue::Id(id);
+            true
+        } else {
+            false
+        }
+    }
+}
+
+impl JmapObjectId for MailRuleProperty {
+    fn as_id(&self) -> Option<Id> {
+        None
+    }
+
+    fn as_any_id(&self) -> Option<AnyId> {
+        None
+    }
+
+    fn as_id_ref(&self) -> Option<&str> {
+        None
+    }
+
+    fn try_set_id(&mut self, _: AnyId) -> bool {
+        false
+    }
+}

crates/jmap-proto/src/object/mod.rs

@@ -28,6 +28,7 @@ pub mod inbuxa_data_inventory; // inbuxa: personal-data catalog
 pub mod inbuxa_inventory_snapshot; // inbuxa: personal-data catalog
 pub mod inbuxa_audit; // inbuxa: the audit log
 pub mod inbuxa_legal_hold; // inbuxa: legal hold
+pub mod inbuxa_mail_rule; // inbuxa: DLP and mail flow rules
 pub mod inbuxa_hold_export; // inbuxa: legal hold exports
 pub mod inbuxa_explanation; // inbuxa: "Explain this" with the local model
 pub mod inbuxa_protocol_policy; // inbuxa: legacy protocols off

crates/jmap-proto/src/references/eval.rs

@@ -82,6 +82,9 @@ impl Response<'_> {
                         GetResponseMethod::LegalHold(response) => {
                             response.eval_jptr(path, &mut results)
                         }
+                        GetResponseMethod::MailRule(response) => {
+                            response.eval_jptr(path, &mut results)
+                        }
                         GetResponseMethod::HoldExport(response) => {
                             response.eval_jptr(path, &mut results)
                         }

crates/jmap-proto/src/references/resolve.rs

@@ -53,6 +53,7 @@ impl Response<'_> {
                 GetRequestMethod::AuditSettings(request) => request.resolve_references(self)?,
                 GetRequestMethod::AccountLock(request) => request.resolve_references(self)?,
                 GetRequestMethod::LegalHold(request) => request.resolve_references(self)?,
+                GetRequestMethod::MailRule(request) => request.resolve_references(self)?,
                 GetRequestMethod::HoldExport(request) => request.resolve_references(self)?,
                 GetRequestMethod::ProtocolPolicy(request) => request.resolve_references(self)?,
                 GetRequestMethod::TenantProtocolPolicy(request) => {
@@ -122,6 +123,9 @@ impl Response<'_> {
                 SetRequestMethod::LegalHold(request) => {
                     request.resolve_references(self, 1, false)?
                 }
+                SetRequestMethod::MailRule(request) => {
+                    request.resolve_references(self, 1, false)?
+                }
                 SetRequestMethod::HoldExport(request) => {
                     request.resolve_references(self, 1, false)?
                 }

crates/jmap-proto/src/request/method.rs

@@ -65,6 +65,8 @@ pub enum MethodObject {
     LegalHold,
     HoldExport,
     ProtocolPolicy,
+    // inbuxa: DLP and mail flow rules
+    MailRule,
     TenantProtocolPolicy,
 }
 
@@ -102,7 +104,8 @@ impl MethodObject {
             | MethodObject::AuditVerification
             | MethodObject::AccountLock
             | MethodObject::LegalHold
-            | MethodObject::HoldExport => Capability::Inbuxa,
+            | MethodObject::HoldExport
+            | MethodObject::MailRule => Capability::Inbuxa,
             MethodObject::ProtocolPolicy => Capability::Inbuxa,
             MethodObject::TenantProtocolPolicy => Capability::Inbuxa,
         }
@@ -296,6 +299,8 @@ impl MethodName {
             (MethodFunction::Set, MethodObject::AccountLock) => "inbuxa:AccountLock/set",
             (MethodFunction::Get, MethodObject::LegalHold) => "inbuxa:LegalHold/get",
             (MethodFunction::Set, MethodObject::LegalHold) => "inbuxa:LegalHold/set",
+            (MethodFunction::Get, MethodObject::MailRule) => "inbuxa:MailRule/get",
+            (MethodFunction::Set, MethodObject::MailRule) => "inbuxa:MailRule/set",
             (MethodFunction::Get, MethodObject::HoldExport) => "inbuxa:HoldExport/get",
             (MethodFunction::Set, MethodObject::HoldExport) => "inbuxa:HoldExport/set",
             (MethodFunction::Set, MethodObject::AuditVerification) => {
@@ -448,6 +453,8 @@ impl MethodName {
             "inbuxa:AccountLock/set" => (MethodObject::AccountLock, MethodFunction::Set),
             "inbuxa:LegalHold/get" => (MethodObject::LegalHold, MethodFunction::Get),
             "inbuxa:LegalHold/set" => (MethodObject::LegalHold, MethodFunction::Set),
+            "inbuxa:MailRule/get" => (MethodObject::MailRule, MethodFunction::Get),
+            "inbuxa:MailRule/set" => (MethodObject::MailRule, MethodFunction::Set),
             "inbuxa:HoldExport/get" => (MethodObject::HoldExport, MethodFunction::Get),
             "inbuxa:HoldExport/set" => (MethodObject::HoldExport, MethodFunction::Set),
             "inbuxa:AuditVerification/set" => (MethodObject::AuditVerification, MethodFunction::Set),
@@ -518,6 +525,7 @@ impl Display for MethodObject {
             MethodObject::AuditVerification => "inbuxa:AuditVerification",
             MethodObject::AccountLock => "inbuxa:AccountLock",
             MethodObject::LegalHold => "inbuxa:LegalHold",
+            MethodObject::MailRule => "inbuxa:MailRule",
             MethodObject::HoldExport => "inbuxa:HoldExport",
             MethodObject::ProtocolPolicy => "inbuxa:ProtocolPolicy",
             MethodObject::TenantProtocolPolicy => "inbuxa:TenantProtocolPolicy",

crates/jmap-proto/src/request/mod.rs

@@ -123,6 +123,7 @@ pub enum GetRequestMethod {
     AuditSettings(Box<GetRequest<crate::object::inbuxa_audit::AuditSettings>>),
     AccountLock(Box<GetRequest<crate::object::inbuxa_account_lock::AccountLock>>),
     LegalHold(Box<GetRequest<crate::object::inbuxa_legal_hold::LegalHold>>),
+    MailRule(Box<GetRequest<crate::object::inbuxa_mail_rule::MailRule>>),
     HoldExport(Box<GetRequest<crate::object::inbuxa_hold_export::HoldExport>>),
     ProtocolPolicy(Box<GetRequest<crate::object::inbuxa_protocol_policy::ProtocolPolicy>>),
     TenantProtocolPolicy(
@@ -158,6 +159,7 @@ pub enum SetRequestMethod<'x> {
     AuditVerification(Box<SetRequest<'x, crate::object::inbuxa_audit::AuditVerification>>),
     AccountLock(Box<SetRequest<'x, crate::object::inbuxa_account_lock::AccountLock>>),
     LegalHold(Box<SetRequest<'x, crate::object::inbuxa_legal_hold::LegalHold>>),
+    MailRule(Box<SetRequest<'x, crate::object::inbuxa_mail_rule::MailRule>>),
     HoldExport(Box<SetRequest<'x, crate::object::inbuxa_hold_export::HoldExport>>),
     ProtocolPolicy(Box<SetRequest<'x, crate::object::inbuxa_protocol_policy::ProtocolPolicy>>),
     TenantProtocolPolicy(

crates/jmap-proto/src/request/parser.rs

@@ -609,6 +609,21 @@ impl<'de> Visitor<'de> for CallVisitor {
                     return Err(de::Error::invalid_length(1, &self));
                 }
             },
+            // inbuxa: DLP and mail flow rules
+            (MethodFunction::Get, MethodObject::MailRule) => match seq.next_element() {
+                Ok(Some(value)) => RequestMethod::Get(GetRequestMethod::MailRule(value)),
+                Err(err) => RequestMethod::invalid(err),
+                Ok(None) => {
+                    return Err(de::Error::invalid_length(1, &self));
+                }
+            },
+            (MethodFunction::Set, MethodObject::MailRule) => match seq.next_element() {
+                Ok(Some(value)) => RequestMethod::Set(SetRequestMethod::MailRule(value)),
+                Err(err) => RequestMethod::invalid(err),
+                Ok(None) => {
+                    return Err(de::Error::invalid_length(1, &self));
+                }
+            },
             // inbuxa: legal hold
             (MethodFunction::Get, MethodObject::LegalHold) => match seq.next_element() {
                 Ok(Some(value)) => RequestMethod::Get(GetRequestMethod::LegalHold(value)),

crates/jmap-proto/src/response/mod.rs

@@ -110,6 +110,7 @@ pub enum GetResponseMethod {
     AuditSettings(GetResponse<crate::object::inbuxa_audit::AuditSettings>),
     AccountLock(GetResponse<crate::object::inbuxa_account_lock::AccountLock>),
     LegalHold(GetResponse<crate::object::inbuxa_legal_hold::LegalHold>),
+    MailRule(GetResponse<crate::object::inbuxa_mail_rule::MailRule>),
     HoldExport(GetResponse<crate::object::inbuxa_hold_export::HoldExport>),
     ProtocolPolicy(GetResponse<crate::object::inbuxa_protocol_policy::ProtocolPolicy>),
     TenantProtocolPolicy(
@@ -145,6 +146,7 @@ pub enum SetResponseMethod {
     AuditVerification(Box<SetResponse<crate::object::inbuxa_audit::AuditVerification>>),
     AccountLock(Box<SetResponse<crate::object::inbuxa_account_lock::AccountLock>>),
     LegalHold(Box<SetResponse<crate::object::inbuxa_legal_hold::LegalHold>>),
+    MailRule(Box<SetResponse<crate::object::inbuxa_mail_rule::MailRule>>),
     HoldExport(Box<SetResponse<crate::object::inbuxa_hold_export::HoldExport>>),
     Explanation(Box<SetResponse<crate::object::inbuxa_explanation::Explanation>>),
     ProtocolPolicy(Box<SetResponse<crate::object::inbuxa_protocol_policy::ProtocolPolicy>>),
@@ -799,6 +801,18 @@ impl<'x> From<SetResponse<crate::object::inbuxa_account_lock::AccountLock>> for
 }
 
 // inbuxa: legal hold
+impl<'x> From<GetResponse<crate::object::inbuxa_mail_rule::MailRule>> for ResponseMethod<'x> {
+    fn from(value: GetResponse<crate::object::inbuxa_mail_rule::MailRule>) -> Self {
+        ResponseMethod::Get(GetResponseMethod::MailRule(value))
+    }
+}
+
+impl<'x> From<SetResponse<crate::object::inbuxa_mail_rule::MailRule>> for ResponseMethod<'x> {
+    fn from(value: SetResponse<crate::object::inbuxa_mail_rule::MailRule>) -> Self {
+        ResponseMethod::Set(SetResponseMethod::MailRule(Box::new(value)))
+    }
+}
+
 impl<'x> From<GetResponse<crate::object::inbuxa_legal_hold::LegalHold>> for ResponseMethod<'x> {
     fn from(value: GetResponse<crate::object::inbuxa_legal_hold::LegalHold>) -> Self {
         ResponseMethod::Get(GetResponseMethod::LegalHold(value))