diff --git a/Cargo.lock b/Cargo.lock
index f624cd5..d14ec2d 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -3947,9 +3947,12 @@ name = "inbuxa-features"
 version = "0.16.22"
 dependencies = [
  "ahash",
+ "aho-corasick",
  "base64 0.23.1",
  "flate2",
  "jmap_proto",
+ "quick-xml 0.41.0",
+ "regex",
  "registry",
  "serde",
  "serde_json",
@@ -3961,6 +3964,7 @@ dependencies = [
  "types",
  "utils",
  "xxhash-rust",
+ "zip",
 ]
 
 [[package]]
diff --git a/crates/features/Cargo.toml b/crates/features/Cargo.toml
index cbee6d6..3054682 100644
--- a/crates/features/Cargo.toml
+++ b/crates/features/Cargo.toml
@@ -21,6 +21,11 @@ base64 = "0.23"
 sha2 = "0.11"
 flate2 = "1.1"
 tokio = { version = "1.53", features = ["sync", "rt"] }
+# inbuxa: DLP detectors and attachment text (dlp-and-mail-flow-rules spec)
+regex = "1.13.1"
+aho-corasick = "1.1"
+zip = "8.6"
+quick-xml = "0.41"
 
 [dev-dependencies]
 tokio = { version = "1.53", features = ["macros", "rt"] }
diff --git a/crates/features/src/lib.rs b/crates/features/src/lib.rs
index 9145a72..9df288c 100644
--- a/crates/features/src/lib.rs
+++ b/crates/features/src/lib.rs
@@ -23,6 +23,7 @@ pub mod audit;
 pub mod branding;
 pub mod hold;
 pub mod lock;
+pub mod mailflow;
 pub mod masked_email;
 pub mod privacy;
 pub mod security;
diff --git a/crates/features/src/mailflow/detectors/any.rs b/crates/features/src/mailflow/detectors/any.rs
new file mode 100644
index 0000000..1120cb7
--- /dev/null
+++ b/crates/features/src/mailflow/detectors/any.rs
@@ -0,0 +1,522 @@
+/*
+ * SPDX-FileCopyrightText: 2026 Coffey Labs
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+//! Detectors that aren't tied to one country (§2.3, region "Any").
+
+use super::{Detector, Findings, Region, Strength, checks, digits, stands_alone, word_near};
+use regex::Regex;
+use std::sync::LazyLock;
+
+pub static DETECTORS: &[Detector] = &[
+    Detector::new(
+        "payment-card",
+        "Payment card number",
+        Region::Any,
+        Strength::Checked,
+        payment_card,
+    ),
+    Detector::new("iban", "IBAN", Region::Any, Strength::Checked, iban),
+    Detector::new(
+        "swift-bic",
+        "SWIFT/BIC code",
+        Region::Any,
+        Strength::NeedsWord,
+        swift_bic,
+    ),
+    Detector::new(
+        "email-addresses",
+        "Email addresses",
+        Region::Any,
+        Strength::Checked,
+        email_addresses,
+    ),
+    Detector::new(
+        "phone-numbers",
+        "Phone numbers",
+        Region::Any,
+        Strength::NeedsWord,
+        phone_numbers,
+    ),
+    Detector::new(
+        "date-of-birth",
+        "Date of birth",
+        Region::Any,
+        Strength::NeedsWord,
+        date_of_birth,
+    ),
+    Detector::new(
+        "passport",
+        "Passport number",
+        Region::Any,
+        Strength::NeedsWord,
+        passport,
+    ),
+    Detector::new(
+        "private-key",
+        "Private key",
+        Region::Any,
+        Strength::Checked,
+        private_key,
+    ),
+    Detector::new(
+        "credentials",
+        "Cloud and service credentials",
+        Region::Any,
+        Strength::Checked,
+        credentials,
+    ),
+];
+
+fn re(pattern: &str) -> Regex {
+    Regex::new(pattern).expect("detector pattern")
+}
+
+// --- Payment cards --------------------------------------------------------
+
+/// Issuer prefixes (ISO/IEC 7812 IINs) and the lengths each network issues.
+fn card_network(number: &str) -> bool {
+    let len = number.len();
+    let prefix = |n: usize| number[..n].parse::<u32>().unwrap_or(0);
+    match number.as_bytes()[0] {
+        // Visa
+        b'4' => matches!(len, 13 | 16 | 19),
+        b'5' => {
+            // Mastercard 51–55; Maestro 50, 56–58
+            (51..=55).contains(&prefix(2)) && len == 16
+                || matches!(prefix(2), 50 | 56..=58) && (12..=19).contains(&len)
+        }
+        // Mastercard 2221–2720
+        b'2' => (2221..=2720).contains(&prefix(4)) && len == 16,
+        b'3' => {
+            // American Express 34, 37; JCB 3528–3589; Diners 300–305, 36, 38, 39
+            matches!(prefix(2), 34 | 37) && len == 15
+                || (3528..=3589).contains(&prefix(4)) && (16..=19).contains(&len)
+                || ((300..=305).contains(&prefix(3)) || matches!(prefix(2), 36 | 38 | 39))
+                    && (14..=19).contains(&len)
+        }
+        // Discover 6011, 644–649, 65; UnionPay 62; Maestro 6x
+        b'6' => (12..=19).contains(&len),
+        _ => false,
+    }
+}
+
+fn is_card(number: &str) -> bool {
+    (12..=19).contains(&number.len()) && card_network(number) && checks::luhn(number)
+}
+
+static CARD: LazyLock<Regex> = LazyLock::new(|| re(r"\b\d(?:[ -]?\d){11,18}\b"));
+
+fn payment_card(text: &str, findings: &mut Findings) {
+    for m in CARD.find_iter(text) {
+        if !stands_alone(text, m.start(), m.end()) {
+            continue;
+        }
+        let whole = digits(m.as_str());
+        if is_card(&whole) {
+            findings.insert(whole);
+            continue;
+        }
+        // Two numbers side by side ("4242 4242 4242 4242 2031"): try each
+        // run of whole groups
+        let groups: Vec<String> = m.as_str().split([' ', '-']).map(digits).collect();
+        'runs: for from in 0..groups.len() {
+            let mut number = String::new();
+            for group in &groups[from..] {
+                number.push_str(group);
+                if is_card(&number) {
+                    findings.insert(number);
+                    break 'runs;
+                }
+            }
+        }
+    }
+}
+
+// --- IBAN -----------------------------------------------------------------
+
+static IBAN: LazyLock<Regex> =
+    LazyLock::new(|| re(r"\b[A-Za-z]{2}\d{2}(?:[ ]?[A-Za-z0-9]){11,30}"));
+
+fn iban(text: &str, findings: &mut Findings) {
+    // The pattern can run on into the next words, even the next IBAN: after
+    // each hit, look again from where that IBAN ended
+    let mut from = 0;
+    while let Some(m) = IBAN.find_at(text, from) {
+        from = m.start() + 1;
+        let compact = m.as_str().replace(' ', "").to_ascii_uppercase();
+        let Some(len) = checks::iban_length(&compact[..2]) else {
+            continue;
+        };
+        if compact.len() < len {
+            continue;
+        }
+        // Where the country's length ends in the text, spaces counted
+        let mut seen = 0;
+        let Some(end) = m
+            .as_str()
+            .char_indices()
+            .find(|(_, c)| {
+                if *c != ' ' {
+                    seen += 1;
+                }
+                seen == len
+            })
+            .map(|(i, c)| m.start() + i + c.len_utf8())
+        else {
+            continue;
+        };
+        let candidate = &compact[..len];
+        if stands_alone(text, m.start(), end) && checks::iban(candidate) {
+            findings.insert(candidate);
+            from = end;
+        }
+    }
+}
+
+// --- SWIFT/BIC ------------------------------------------------------------
+
+static BIC: LazyLock<Regex> =
+    LazyLock::new(|| re(r"\b[A-Z]{4}[A-Z]{2}[A-Z0-9]{2}(?:[A-Z0-9]{3})?\b"));
+
+const BIC_WORDS: &[&str] = &[
+    "swift",
+    "bic",
+    "swift/bic",
+    "bank",
+    "banque",
+    "bankverbindung",
+];
+
+fn swift_bic(text: &str, findings: &mut Findings) {
+    for m in BIC.find_iter(text) {
+        let code = m.as_str();
+        if checks::is_country(&code[4..6]) && word_near(text, m.start(), m.end(), BIC_WORDS) {
+            findings.insert(code);
+        }
+    }
+}
+
+// --- Contact lists --------------------------------------------------------
+
+static EMAIL: LazyLock<Regex> =
+    LazyLock::new(|| re(r"(?i)\b[a-z0-9._%+-]+@[a-z0-9-]+(?:\.[a-z0-9-]+)*\.[a-z]{2,}\b"));
+
+fn email_addresses(text: &str, findings: &mut Findings) {
+    for m in EMAIL.find_iter(text) {
+        findings.insert(m.as_str().to_lowercase());
+    }
+}
+
+/// International form: found alone. National form: only with a word.
+static PHONE_INTL: LazyLock<Regex> = LazyLock::new(|| re(r"\+\d{1,3}(?:[ .-]?\(?\d{1,4}\)?){2,5}"));
+static PHONE_NATIONAL: LazyLock<Regex> =
+    LazyLock::new(|| re(r"\(?\d{2,4}\)?[ .-]\d{3,4}[ .-]\d{3,4}"));
+
+const PHONE_WORDS: &[&str] = &[
+    "phone",
+    "tel",
+    "telephone",
+    "mobile",
+    "cell",
+    "fax",
+    "telefon",
+    "téléphone",
+    "teléfono",
+    "telefono",
+    "handy",
+    "portable",
+    "móvil",
+    "cellulare",
+    "mobiel",
+];
+
+fn phone_numbers(text: &str, findings: &mut Findings) {
+    let mut international = Vec::new();
+    for m in PHONE_INTL.find_iter(text) {
+        let number = digits(m.as_str());
+        if (8..=15).contains(&number.len()) && stands_alone(text, m.start() + 1, m.end()) {
+            findings.insert(number);
+            international.push(m.range());
+        }
+    }
+    for m in PHONE_NATIONAL.find_iter(text) {
+        let number = digits(m.as_str());
+        // Not the tail of an international number already counted
+        if international.iter().any(|r| r.contains(&m.start())) {
+            continue;
+        }
+        if (9..=11).contains(&number.len())
+            && stands_alone(text, m.start(), m.end())
+            && !text[..m.start()].ends_with('+')
+            && word_near(text, m.start(), m.end(), PHONE_WORDS)
+        {
+            findings.insert(number);
+        }
+    }
+}
+
+// --- Date of birth --------------------------------------------------------
+
+static DATE_ISO: LazyLock<Regex> = LazyLock::new(|| re(r"\b(\d{4})-(\d{2})-(\d{2})\b"));
+static DATE_NUMERIC: LazyLock<Regex> =
+    LazyLock::new(|| re(r"\b(\d{1,2})[./-](\d{1,2})[./-](\d{4})\b"));
+static DATE_WORDS: LazyLock<Regex> = LazyLock::new(|| {
+    re(
+        r"(?i)\b(?:(\d{1,2})\s+(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)[a-z]*\.?,?\s+(\d{4})|(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)[a-z]*\.?\s+(\d{1,2}),?\s+(\d{4}))\b",
+    )
+});
+
+const BIRTH_WORDS: &[&str] = &[
+    "born",
+    "birth",
+    "dob",
+    "d.o.b",
+    "birthday",
+    "birthdate",
+    "geburtsdatum",
+    "geboren",
+    "naissance",
+    "né le",
+    "née le",
+    "nacimiento",
+    "nacido",
+    "nacida",
+    "nascita",
+    "nato il",
+    "nata il",
+    "geboortedatum",
+    "födelsedatum",
+    "fødselsdato",
+    "syntymäaika",
+    "urodzenia",
+    "nascimento",
+];
+
+fn valid_date(year: u32, month: u32, day: u32) -> bool {
+    let days = match month {
+        1 | 3 | 5 | 7 | 8 | 10 | 12 => 31,
+        4 | 6 | 9 | 11 => 30,
+        2 if year.is_multiple_of(4) && (!year.is_multiple_of(100) || year.is_multiple_of(400)) => {
+            29
+        }
+        2 => 28,
+        _ => return false,
+    };
+    (1900..=2100).contains(&year) && (1..=days).contains(&day)
+}
+
+fn month_number(name: &str) -> u32 {
+    const MONTHS: [&str; 12] = [
+        "jan", "feb", "mar", "apr", "may", "jun", "jul", "aug", "sep", "oct", "nov", "dec",
+    ];
+    let name = name.to_lowercase();
+    MONTHS
+        .iter()
+        .position(|m| *m == name)
+        .map_or(0, |i| i as u32 + 1)
+}
+
+fn date_of_birth(text: &str, findings: &mut Findings) {
+    let mut add = |start: usize, end: usize, key: String| {
+        if word_near(text, start, end, BIRTH_WORDS) {
+            findings.insert(key);
+        }
+    };
+    let num = |s: &str| s.parse::<u32>().unwrap_or(0);
+    for c in DATE_ISO.captures_iter(text) {
+        let (y, m, d) = (num(&c[1]), num(&c[2]), num(&c[3]));
+        let whole = c.get(0).unwrap();
+        if valid_date(y, m, d) {
+            add(whole.start(), whole.end(), format!("{y:04}{m:02}{d:02}"));
+        }
+    }
+    for c in DATE_NUMERIC.captures_iter(text) {
+        let (a, b, y) = (num(&c[1]), num(&c[2]), num(&c[3]));
+        let whole = c.get(0).unwrap();
+        // Day first or month first: either reading that is a real date
+        if valid_date(y, b, a) || valid_date(y, a, b) {
+            add(whole.start(), whole.end(), whole.as_str().to_string());
+        }
+    }
+    for c in DATE_WORDS.captures_iter(text) {
+        let whole = c.get(0).unwrap();
+        let (d, m, y) = match (c.get(1), c.get(4)) {
+            (Some(d), _) => (num(d.as_str()), month_number(&c[2]), num(&c[3])),
+            (_, Some(m)) => (num(&c[5]), month_number(m.as_str()), num(&c[6])),
+            _ => continue,
+        };
+        if valid_date(y, m, d) {
+            add(whole.start(), whole.end(), format!("{y:04}{m:02}{d:02}"));
+        }
+    }
+}
+
+// --- Passport -------------------------------------------------------------
+
+static PASSPORT: LazyLock<Regex> = LazyLock::new(|| re(r"\b[A-Z0-9]{6,9}\b"));
+
+const PASSPORT_WORDS: &[&str] = &[
+    "passport",
+    "passeport",
+    "reisepass",
+    "pasaporte",
+    "passaporto",
+    "paspoort",
+    "passnummer",
+    "pass-nr",
+    "passport no",
+    "pasaporte n.º",
+    "passaporte",
+];
+
+fn passport(text: &str, findings: &mut Findings) {
+    for m in PASSPORT.find_iter(text) {
+        let value = m.as_str();
+        if value.bytes().filter(u8::is_ascii_digit).count() >= 5
+            && word_near(text, m.start(), m.end(), PASSPORT_WORDS)
+        {
+            findings.insert(value);
+        }
+    }
+}
+
+// --- Keys and credentials -------------------------------------------------
+
+static PRIVATE_KEY: LazyLock<Regex> = LazyLock::new(|| {
+    re(
+        r"-----BEGIN (?:(?:RSA|EC|DSA|OPENSSH|ENCRYPTED|PGP) )?PRIVATE KEY(?: BLOCK)?-----\s*([A-Za-z0-9+/=:\s-]{0,64})",
+    )
+});
+
+fn private_key(text: &str, findings: &mut Findings) {
+    for c in PRIVATE_KEY.captures_iter(text) {
+        // Each key once, by the start of its body
+        let body: String = c[1].chars().filter(|c| !c.is_whitespace()).collect();
+        let whole = c.get(0).unwrap();
+        findings.insert(if body.is_empty() {
+            format!("@{}", whole.start())
+        } else {
+            body
+        });
+    }
+}
+
+/// Published token formats: AWS access key IDs, GitHub tokens, Slack
+/// tokens, Stripe live secret and restricted keys, Google API keys.
+static CREDENTIAL: LazyLock<Regex> = LazyLock::new(|| {
+    re(concat!(
+        r"\b(?:",
+        r"(?:AKIA|ASIA|ABIA|ACCA)[A-Z0-9]{16}",
+        r"|gh[pousr]_[A-Za-z0-9]{36}",
+        r"|github_pat_[A-Za-z0-9_]{82}",
+        r"|xox[abposr]-[A-Za-z0-9-]{10,72}",
+        r"|(?:sk|rk)_live_[A-Za-z0-9]{24,99}",
+        r"|AIza[0-9A-Za-z_-]{35}",
+        r")\b"
+    ))
+});
+
+fn credentials(text: &str, findings: &mut Findings) {
+    for m in CREDENTIAL.find_iter(text) {
+        findings.insert(m.as_str());
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::mailflow::detectors::by_id;
+
+    fn count(id: &str, text: &str) -> usize {
+        by_id(id).unwrap().count(text)
+    }
+
+    #[test]
+    fn payment_cards() {
+        // Networks' and processors' published test numbers
+        let text = "Visa 4242 4242 4242 4242, MC 5555-5555-5555-4444, Amex 378282246310005, \
+                    Discover 6011111111111117, JCB 3566002020360505, Diners 30569309025904, \
+                    UnionPay 6200000000000005, Mastercard 2-series 2223003122003222";
+        assert_eq!(count("payment-card", text), 8);
+        // Luhn fails, wrong network length, inside a longer number
+        assert_eq!(count("payment-card", "4242424242424241"), 0);
+        assert_eq!(count("payment-card", "378282246310005 0"), 1);
+        assert_eq!(count("payment-card", "order 94242424242424242 shipped"), 0);
+        // The same number twice counts once
+        assert_eq!(
+            count("payment-card", "4242424242424242 and 4242-4242-4242-4242"),
+            1
+        );
+        // A card followed by a year
+        assert_eq!(count("payment-card", "card 4242 4242 4242 4242 2031"), 1);
+    }
+
+    #[test]
+    fn ibans() {
+        let text =
+            "Pay GB29 NWBK 6016 1331 9268 19 or de89370400440532013000 (NL91ABNA0417164300).";
+        assert_eq!(count("iban", text), 3);
+        assert_eq!(count("iban", "GB29 NWBK 6016 1331 9268 18"), 0);
+        // Runs into the next word: still found at the country's length
+        assert_eq!(count("iban", "IBAN NL91ABNA0417164300 BIC ABNANL2A"), 1);
+    }
+
+    #[test]
+    fn swift_codes_need_a_word() {
+        assert_eq!(count("swift-bic", "SWIFT: DEUTDEFF500"), 1);
+        assert_eq!(count("swift-bic", "BIC NWBKGB2L"), 1);
+        assert_eq!(count("swift-bic", "HAPPYDAYS DEUTDEFF"), 0);
+        // Not a country in positions 5–6
+        assert_eq!(count("swift-bic", "BIC DEUTZZFF"), 0);
+    }
+
+    #[test]
+    fn email_and_phone_lists() {
+        let list = "a@example.com, B@Example.com, c.d+x@mail.example.org, a@example.com";
+        assert_eq!(count("email-addresses", list), 3);
+        assert_eq!(
+            count("phone-numbers", "+44 20 7946 0958, +1 (415) 555-2671"),
+            2
+        );
+        assert_eq!(count("phone-numbers", "call 020 7946 0958"), 0);
+        assert_eq!(count("phone-numbers", "Tel: 020 7946 0958"), 1);
+        assert_eq!(count("phone-numbers", "invoice 020 7946 0958"), 0);
+        // One number, not also its national tail
+        assert_eq!(count("phone-numbers", "Tel: +44 20 7946 0958"), 1);
+    }
+
+    #[test]
+    fn dates_of_birth() {
+        assert_eq!(count("date-of-birth", "DOB: 1984-02-29"), 1);
+        assert_eq!(count("date-of-birth", "Geburtsdatum 31.12.1970"), 1);
+        assert_eq!(count("date-of-birth", "born on March 3, 1962"), 1);
+        assert_eq!(count("date-of-birth", "date of birth 3 Mar 1962"), 1);
+        // Not a real date, no word, a meeting
+        assert_eq!(count("date-of-birth", "DOB: 1985-02-29"), 0);
+        assert_eq!(count("date-of-birth", "invoice 1984-02-29"), 0);
+        assert_eq!(count("date-of-birth", "Meeting on 12/05/2026"), 0);
+    }
+
+    #[test]
+    fn passports_need_a_word() {
+        assert_eq!(count("passport", "Passport number: 533380006"), 1);
+        assert_eq!(count("passport", "Reisepass C01X00T47"), 1);
+        assert_eq!(count("passport", "Order 533380006 shipped"), 0);
+        // Mostly letters: a word, not a number
+        assert_eq!(count("passport", "passport PASSWORD"), 0);
+    }
+
+    #[test]
+    fn keys_and_credentials() {
+        let key = "-----BEGIN OPENSSH PRIVATE KEY-----\nb3BlbnNzaC1rZXktdjEAAAAABG5vbmUAAAAEbm9uZQ\n-----END OPENSSH PRIVATE KEY-----";
+        assert_eq!(count("private-key", key), 1);
+        assert_eq!(count("private-key", "-----BEGIN PUBLIC KEY-----\nMFkw"), 0);
+        // Documentation examples of each format
+        let tokens = "AKIAIOSFODNN7EXAMPLE ghp_0123456789abcdefghijklmnopqrstuvwxyz \
+                      AIzaSyA-0123456789abcdefghijklmnopqrstu";
+        assert_eq!(count("credentials", tokens), 3);
+        assert_eq!(count("credentials", "AKIA123 ghp_short"), 0);
+    }
+}
diff --git a/crates/features/src/mailflow/detectors/checks.rs b/crates/features/src/mailflow/detectors/checks.rs
new file mode 100644
index 0000000..d0320be
--- /dev/null
+++ b/crates/features/src/mailflow/detectors/checks.rs
@@ -0,0 +1,227 @@
+/*
+ * SPDX-FileCopyrightText: 2026 Coffey Labs
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+//! Check-digit algorithms, each from its public definition.
+
+/// The Luhn check (ISO/IEC 7812-1, Annex B) over a string of ASCII digits.
+pub fn luhn(digits: &str) -> bool {
+    if digits.len() < 2 || !digits.bytes().all(|b| b.is_ascii_digit()) {
+        return false;
+    }
+    let sum: u32 = digits
+        .bytes()
+        .rev()
+        .enumerate()
+        .map(|(i, b)| {
+            let d = u32::from(b - b'0');
+            if i % 2 == 1 {
+                let d = d * 2;
+                if d > 9 { d - 9 } else { d }
+            } else {
+                d
+            }
+        })
+        .sum();
+    sum % 10 == 0
+}
+
+/// ISO 13616 IBAN lengths, by country, from the IBAN registry.
+const IBAN_LENGTHS: &[(&str, usize)] = &[
+    ("AD", 24),
+    ("AE", 23),
+    ("AL", 28),
+    ("AT", 20),
+    ("AZ", 28),
+    ("BA", 20),
+    ("BE", 16),
+    ("BG", 22),
+    ("BH", 22),
+    ("BI", 27),
+    ("BR", 29),
+    ("BY", 28),
+    ("CH", 21),
+    ("CR", 22),
+    ("CY", 28),
+    ("CZ", 24),
+    ("DE", 22),
+    ("DJ", 27),
+    ("DK", 18),
+    ("DO", 28),
+    ("EE", 20),
+    ("EG", 29),
+    ("ES", 24),
+    ("FI", 18),
+    ("FK", 18),
+    ("FO", 18),
+    ("FR", 27),
+    ("GB", 22),
+    ("GE", 22),
+    ("GI", 23),
+    ("GL", 18),
+    ("GR", 27),
+    ("GT", 28),
+    ("HN", 28),
+    ("HR", 21),
+    ("HU", 28),
+    ("IE", 22),
+    ("IL", 23),
+    ("IQ", 23),
+    ("IS", 26),
+    ("IT", 27),
+    ("JO", 30),
+    ("KW", 30),
+    ("KZ", 20),
+    ("LB", 28),
+    ("LC", 32),
+    ("LI", 21),
+    ("LT", 20),
+    ("LU", 20),
+    ("LV", 21),
+    ("LY", 25),
+    ("MC", 27),
+    ("MD", 24),
+    ("ME", 22),
+    ("MK", 19),
+    ("MN", 20),
+    ("MR", 27),
+    ("MT", 31),
+    ("MU", 30),
+    ("NI", 28),
+    ("NL", 18),
+    ("NO", 15),
+    ("OM", 23),
+    ("PK", 24),
+    ("PL", 28),
+    ("PS", 29),
+    ("PT", 25),
+    ("QA", 29),
+    ("RO", 24),
+    ("RS", 22),
+    ("RU", 33),
+    ("SA", 24),
+    ("SC", 31),
+    ("SD", 18),
+    ("SE", 24),
+    ("SI", 19),
+    ("SK", 24),
+    ("SM", 27),
+    ("SO", 23),
+    ("ST", 25),
+    ("SV", 28),
+    ("TL", 23),
+    ("TN", 24),
+    ("TR", 26),
+    ("UA", 29),
+    ("VA", 22),
+    ("VG", 24),
+    ("XK", 20),
+    ("YE", 30),
+];
+
+/// The IBAN length for a country code, if the country uses IBANs.
+pub fn iban_length(country: &str) -> Option<usize> {
+    IBAN_LENGTHS
+        .iter()
+        .find(|(code, _)| *code == country)
+        .map(|(_, len)| *len)
+}
+
+/// ISO 13616 / ISO 7064 MOD 97-10 over an IBAN with no spaces, upper case:
+/// move the first four characters to the end, turn letters into 10–35, and
+/// the number mod 97 must be 1. Also checks the country's length.
+pub fn iban(iban: &str) -> bool {
+    if iban.len() < 5
+        || !iban
+            .bytes()
+            .all(|b| b.is_ascii_uppercase() || b.is_ascii_digit())
+    {
+        return false;
+    }
+    if iban_length(&iban[..2]) != Some(iban.len())
+        || !iban[2..4].bytes().all(|b| b.is_ascii_digit())
+    {
+        return false;
+    }
+    let mut remainder: u32 = 0;
+    for b in iban[4..].bytes().chain(iban[..4].bytes()) {
+        let value = if b.is_ascii_digit() {
+            u32::from(b - b'0')
+        } else {
+            u32::from(b - b'A') + 10
+        };
+        remainder = if value >= 10 {
+            (remainder * 100 + value) % 97
+        } else {
+            (remainder * 10 + value) % 97
+        };
+    }
+    remainder == 1
+}
+
+/// ISO 3166-1 alpha-2 country codes, for SWIFT/BIC positions 5–6.
+const COUNTRIES: &str = "AD AE AF AG AI AL AM AO AQ AR AS AT AU AW AX AZ BA BB BD BE BF BG BH BI BJ \
+BL BM BN BO BQ BR BS BT BV BW BY BZ CA CC CD CF CG CH CI CK CL CM CN CO CR CU CV CW CX CY CZ DE DJ \
+DK DM DO DZ EC EE EG EH ER ES ET FI FJ FK FM FO FR GA GB GD GE GF GG GH GI GL GM GN GP GQ GR GS GT \
+GU GW GY HK HM HN HR HT HU ID IE IL IM IN IO IQ IR IS IT JE JM JO JP KE KG KH KI KM KN KP KR KW KY \
+KZ LA LB LC LI LK LR LS LT LU LV LY MA MC MD ME MF MG MH MK ML MM MN MO MP MQ MR MS MT MU MV MW MX \
+MY MZ NA NC NE NF NG NI NL NO NP NR NU NZ OM PA PE PF PG PH PK PL PM PN PR PS PT PW PY QA RE RO RS \
+RU RW SA SB SC SD SE SG SH SI SJ SK SL SM SN SO SR SS ST SV SX SY SZ TC TD TF TG TH TJ TK TL TM TN \
+TO TR TT TV TW TZ UA UG UM US UY UZ VA VC VE VG VI VN VU WF WS XK YE YT ZA ZM ZW";
+
+pub fn is_country(code: &str) -> bool {
+    code.len() == 2 && COUNTRIES.split(' ').any(|c| c == code)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn luhn_known_numbers() {
+        // Published test card numbers
+        for good in [
+            "4242424242424242",
+            "5555555555554444",
+            "378282246310005",
+            "79927398713",
+        ] {
+            assert!(luhn(good), "{good}");
+        }
+        for bad in ["4242424242424241", "79927398710", "1", "12a4"] {
+            assert!(!luhn(bad), "{bad}");
+        }
+    }
+
+    #[test]
+    fn iban_registry_examples() {
+        // The IBAN registry's own examples
+        for good in [
+            "GB29NWBK60161331926819",
+            "DE89370400440532013000",
+            "FR1420041010050500013M02606",
+            "NL91ABNA0417164300",
+            "BE68539007547034",
+            "NO9386011117947",
+            "CH9300762011623852957",
+        ] {
+            assert!(iban(good), "{good}");
+        }
+        for bad in [
+            "GB29NWBK60161331926818", // check fails
+            "GB29NWBK6016133192681",  // too short for GB
+            "ZZ29NWBK60161331926819", // no such country
+            "DE8937040044053201300A", // letters where DE has none still fail mod 97
+        ] {
+            assert!(!iban(bad), "{bad}");
+        }
+    }
+
+    #[test]
+    fn countries() {
+        assert!(is_country("DE") && is_country("US") && is_country("XK"));
+        assert!(!is_country("ZZ") && !is_country("D"));
+    }
+}
diff --git a/crates/features/src/mailflow/detectors/mod.rs b/crates/features/src/mailflow/detectors/mod.rs
new file mode 100644
index 0000000..66b1eab
--- /dev/null
+++ b/crates/features/src/mailflow/detectors/mod.rs
@@ -0,0 +1,199 @@
+/*
+ * SPDX-FileCopyrightText: 2026 Coffey Labs
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+//! Detectors (dlp-and-mail-flow-rules spec, §2.3): each finds one kind of
+//! identifier in text and reports the distinct ones it found.
+//!
+//! A detector is one of two strengths:
+//!
+//! - **Checked**: the identifier carries a published check digit or
+//!   checksum, so a random number rarely passes; found on its own.
+//! - **Needs a word**: the format alone is too common, so a candidate counts
+//!   only with a corroborating word within [`WINDOW`] characters either
+//!   side.
+//!
+//! Findings are distinct normalized values (digits only, upper case), so the
+//! same card number pasted twice counts once. They stay in memory: callers
+//! read only [`Findings::len`].
+
+pub mod any;
+pub mod checks;
+
+use ahash::AHashSet;
+
+/// How far, in characters, a corroborating word may be from a candidate.
+pub const WINDOW: usize = 50;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum Strength {
+    Checked,
+    NeedsWord,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum Region {
+    Any,
+    Us,
+    Uk,
+    Canada,
+    Australia,
+    Eu,
+    Europe,
+    Asia,
+    Americas,
+    Africa,
+}
+
+/// The distinct values one detector found.
+#[derive(Debug, Default)]
+pub struct Findings(AHashSet<String>);
+
+impl Findings {
+    pub fn insert(&mut self, value: impl Into<String>) {
+        self.0.insert(value.into());
+    }
+
+    pub fn len(&self) -> usize {
+        self.0.len()
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.0.is_empty()
+    }
+}
+
+pub struct Detector {
+    /// Stable id, stored in rules: `payment-card`, `iban`, `us-ssn`.
+    pub id: &'static str,
+    pub name: &'static str,
+    pub region: Region,
+    pub strength: Strength,
+    find: fn(&str, &mut Findings),
+}
+
+impl Detector {
+    pub const fn new(
+        id: &'static str,
+        name: &'static str,
+        region: Region,
+        strength: Strength,
+        find: fn(&str, &mut Findings),
+    ) -> Self {
+        Self {
+            id,
+            name,
+            region,
+            strength,
+            find,
+        }
+    }
+
+    /// Adds what this detector finds in `text` to `findings`. Call once per
+    /// piece of text (subject, each part, each attachment) with the same
+    /// `findings`, then read its length.
+    pub fn find(&self, text: &str, findings: &mut Findings) {
+        (self.find)(text, findings)
+    }
+
+    /// The distinct values found in one text.
+    pub fn count(&self, text: &str) -> usize {
+        let mut findings = Findings::default();
+        self.find(text, &mut findings);
+        findings.len()
+    }
+}
+
+/// Every detector, in the order the console lists them.
+pub fn all() -> impl Iterator<Item = &'static Detector> {
+    any::DETECTORS.iter()
+}
+
+pub fn by_id(id: &str) -> Option<&'static Detector> {
+    all().find(|detector| detector.id == id)
+}
+
+/// Whether one of `words` appears, as a whole word and ignoring case, within
+/// [`WINDOW`] characters before `start` or after `end` (byte offsets of the
+/// candidate in `text`). The window is widened by the longest word, so a
+/// word that reaches into it still counts whole.
+pub fn word_near(text: &str, start: usize, end: usize, words: &[&str]) -> bool {
+    let reach = WINDOW + words.iter().map(|w| w.chars().count()).max().unwrap_or(0);
+    let before = text[..start]
+        .char_indices()
+        .rev()
+        .nth(reach - 1)
+        .map_or(0, |(i, _)| i);
+    let after = text[end..]
+        .char_indices()
+        .nth(reach)
+        .map_or(text.len(), |(i, _)| end + i);
+    let window = text[before..after].to_lowercase();
+    words.iter().any(|word| contains_word(&window, word))
+}
+
+/// Whether `word` (lower case) appears in `haystack` (lower case) with no
+/// letter or digit on either side.
+pub fn contains_word(haystack: &str, word: &str) -> bool {
+    haystack.match_indices(word).any(|(i, _)| {
+        let before_ok = haystack[..i]
+            .chars()
+            .next_back()
+            .is_none_or(|c| !c.is_alphanumeric());
+        let after_ok = haystack[i + word.len()..]
+            .chars()
+            .next()
+            .is_none_or(|c| !c.is_alphanumeric());
+        before_ok && after_ok
+    })
+}
+
+/// Whether the match at `start..end` stands alone: no digit or letter
+/// directly before or after it, so `123-45-6789` isn't found inside a
+/// longer run of digits.
+pub fn stands_alone(text: &str, start: usize, end: usize) -> bool {
+    let before = text[..start].chars().next_back();
+    let after = text[end..].chars().next();
+    before.is_none_or(|c| !c.is_alphanumeric()) && after.is_none_or(|c| !c.is_alphanumeric())
+}
+
+/// The ASCII digits of `s`.
+pub fn digits(s: &str) -> String {
+    s.chars().filter(char::is_ascii_digit).collect()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn words_are_whole_and_near() {
+        let text = "Your passport number is X1234567, thanks";
+        let start = text.find("X123").unwrap();
+        assert!(word_near(text, start, start + 8, &["passport"]));
+        assert!(!word_near(text, start, start + 8, &["pass"]));
+        let far = format!("passport{}X1234567", " ".repeat(60));
+        let start = far.find("X123").unwrap();
+        assert!(!word_near(&far, start, start + 8, &["passport"]));
+    }
+
+    #[test]
+    fn near_counts_characters_not_bytes() {
+        // 45 two-byte characters between the word and the candidate: within
+        // 50 characters, though over 50 bytes
+        let text = format!("passport {} X1234567", "é".repeat(45));
+        let start = text.find("X123").unwrap();
+        assert!(word_near(&text, start, start + 8, &["passport"]));
+    }
+
+    #[test]
+    fn ids_are_unique() {
+        let mut seen = AHashSet::new();
+        for detector in all() {
+            assert!(seen.insert(detector.id), "duplicate id {}", detector.id);
+            assert!(by_id(detector.id).is_some());
+        }
+    }
+}
diff --git a/crates/features/src/mailflow/extract.rs b/crates/features/src/mailflow/extract.rs
new file mode 100644
index 0000000..ff233ff
--- /dev/null
+++ b/crates/features/src/mailflow/extract.rs
@@ -0,0 +1,692 @@
+/*
+ * SPDX-FileCopyrightText: 2026 Coffey Labs
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+//! The text of an attachment, for the detectors (§2.3), or why there isn't
+//! one.
+//!
+//! Read: text files (plain, CSV, JSON, XML, HTML), Office Open XML (DOCX,
+//! XLSX, PPTX) and OpenDocument (ODT, ODS, ODP) documents, and ZIP archives
+//! one level deep. **Can't be inspected**: encrypted or password-protected
+//! files, PDF (settled answer 2), the older binary Office formats, archives
+//! inside archives, and anything past the limits. Everything else (images,
+//! audio, programs) has no text to read and is neither.
+//!
+//! Office files are ZIP archives of XML, read here with the `zip` and
+//! `quick-xml` crates the server already uses: no outside converter runs.
+
+use quick_xml::{Reader, XmlVersion, events::Event};
+use std::io::{Cursor, Read};
+
+/// How much may be unpacked from one attachment, and from how many entries.
+#[derive(Debug, Clone, Copy)]
+pub struct Limits {
+    pub max_unpacked: u64,
+    pub max_entries: usize,
+}
+
+impl Default for Limits {
+    fn default() -> Self {
+        Self {
+            max_unpacked: 50 * 1024 * 1024,
+            max_entries: 10_000,
+        }
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum Extracted {
+    /// The text to check.
+    Text(String),
+    /// A kind of file with no text in it: nothing to check, nothing missed.
+    NoText,
+    /// A file that may hold text the detectors couldn't read.
+    NotInspectable(Why),
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum Why {
+    Encrypted,
+    Pdf,
+    LegacyOffice,
+    NestedArchive,
+    TooLarge,
+    Damaged,
+}
+
+impl Why {
+    pub fn as_str(&self) -> &'static str {
+        match self {
+            Why::Encrypted => "encrypted",
+            Why::Pdf => "pdf",
+            Why::LegacyOffice => "legacy-office",
+            Why::NestedArchive => "nested-archive",
+            Why::TooLarge => "too-large",
+            Why::Damaged => "damaged",
+        }
+    }
+}
+
+const OLE_MAGIC: &[u8] = &[0xD0, 0xCF, 0x11, 0xE0, 0xA1, 0xB1, 0x1A, 0xE1];
+const ZIP_MAGIC: &[u8] = b"PK\x03\x04";
+
+/// What an attachment says, from its declared type, its file name and, above
+/// all, its first bytes.
+pub fn extract(
+    content_type: &str,
+    file_name: Option<&str>,
+    data: &[u8],
+    limits: &Limits,
+) -> Extracted {
+    extract_at(content_type, file_name, data, limits, 0)
+}
+
+fn extract_at(
+    content_type: &str,
+    file_name: Option<&str>,
+    data: &[u8],
+    limits: &Limits,
+    depth: u8,
+) -> Extracted {
+    let content_type = content_type.to_ascii_lowercase();
+    let extension = file_name
+        .and_then(|name| name.rsplit_once('.'))
+        .map(|(_, ext)| ext.to_ascii_lowercase())
+        .unwrap_or_default();
+
+    if data.len() as u64 > limits.max_unpacked {
+        return Extracted::NotInspectable(Why::TooLarge);
+    }
+    if data.starts_with(b"%PDF-") || content_type == "application/pdf" || extension == "pdf" {
+        return Extracted::NotInspectable(Why::Pdf);
+    }
+    if data.starts_with(OLE_MAGIC) {
+        // An encrypted OOXML file is an OLE container holding the encrypted
+        // package; any other OLE file is a legacy .doc, .xls or .ppt
+        return Extracted::NotInspectable(if has_utf16(data, "EncryptedPackage") {
+            Why::Encrypted
+        } else {
+            Why::LegacyOffice
+        });
+    }
+    if data.starts_with(ZIP_MAGIC) {
+        if depth > 0 {
+            return Extracted::NotInspectable(Why::NestedArchive);
+        }
+        return zip(data, limits);
+    }
+    if is_text(&content_type, &extension) {
+        let text = decode_text(data);
+        return Extracted::Text(
+            if content_type == "text/html" || matches!(extension.as_str(), "html" | "htm") {
+                strip_html(&text)
+            } else {
+                text
+            },
+        );
+    }
+    Extracted::NoText
+}
+
+fn is_text(content_type: &str, extension: &str) -> bool {
+    content_type.starts_with("text/")
+        || matches!(
+            content_type,
+            "application/json"
+                | "application/xml"
+                | "application/csv"
+                | "application/x-csv"
+                | "message/rfc822"
+        )
+        || matches!(
+            extension,
+            "txt"
+                | "csv"
+                | "tsv"
+                | "json"
+                | "xml"
+                | "md"
+                | "log"
+                | "html"
+                | "htm"
+                | "eml"
+                | "ics"
+                | "vcf"
+        )
+}
+
+/// UTF-16 with a byte order mark, else UTF-8 (lossy).
+fn decode_text(data: &[u8]) -> String {
+    let utf16 = |bytes: &[u8], big: bool| {
+        let units: Vec<u16> = bytes
+            .chunks_exact(2)
+            .map(|c| {
+                if big {
+                    u16::from_be_bytes([c[0], c[1]])
+                } else {
+                    u16::from_le_bytes([c[0], c[1]])
+                }
+            })
+            .collect();
+        String::from_utf16_lossy(&units)
+    };
+    match data {
+        [0xFF, 0xFE, rest @ ..] => utf16(rest, false),
+        [0xFE, 0xFF, rest @ ..] => utf16(rest, true),
+        [0xEF, 0xBB, 0xBF, rest @ ..] => String::from_utf8_lossy(rest).into_owned(),
+        _ => String::from_utf8_lossy(data).into_owned(),
+    }
+}
+
+fn has_utf16(data: &[u8], needle: &str) -> bool {
+    let needle: Vec<u8> = needle.encode_utf16().flat_map(u16::to_le_bytes).collect();
+    data.windows(needle.len()).any(|w| w == needle.as_slice())
+}
+
+/// Tags out, the common entities decoded, block ends as new lines.
+fn strip_html(html: &str) -> String {
+    let mut out = String::with_capacity(html.len());
+    let mut in_tag = false;
+    let mut skip_until: Option<&str> = None;
+    let lower = html.to_ascii_lowercase();
+    let mut i = 0;
+    let bytes = html.as_bytes();
+    while i < bytes.len() {
+        if let Some(end) = skip_until {
+            match lower[i..].find(end) {
+                Some(at) => {
+                    i += at + end.len();
+                    skip_until = None;
+                }
+                None => break,
+            }
+            continue;
+        }
+        let c = bytes[i];
+        if in_tag {
+            if c == b'>' {
+                in_tag = false;
+            }
+            i += 1;
+            continue;
+        }
+        if c == b'<' {
+            if lower[i..].starts_with("<script") {
+                skip_until = Some("</script>");
+            } else if lower[i..].starts_with("<style") {
+                skip_until = Some("</style>");
+            } else {
+                if [
+                    "<br", "<p", "</p", "<div", "</div", "<tr", "<li", "<td", "<th",
+                ]
+                .iter()
+                .any(|t| lower[i..].starts_with(t))
+                {
+                    out.push(
+                        if lower[i..].starts_with("<td") || lower[i..].starts_with("<th") {
+                            '\t'
+                        } else {
+                            '\n'
+                        },
+                    );
+                }
+                in_tag = true;
+            }
+            i += 1;
+            continue;
+        }
+        // Copy up to the next tag
+        let next = html[i..].find('<').map_or(html.len(), |at| i + at);
+        out.push_str(&html[i..next]);
+        i = next;
+    }
+    for (entity, text) in [
+        ("&nbsp;", " "),
+        ("&lt;", "<"),
+        ("&gt;", ">"),
+        ("&quot;", "\""),
+        ("&#39;", "'"),
+        ("&amp;", "&"),
+    ] {
+        out = out.replace(entity, text);
+    }
+    out
+}
+
+/// A ZIP file: an Office document, an OpenDocument, or an archive.
+fn zip(data: &[u8], limits: &Limits) -> Extracted {
+    let Ok(mut archive) = zip::ZipArchive::new(Cursor::new(data)) else {
+        return Extracted::NotInspectable(Why::Damaged);
+    };
+    if archive.len() > limits.max_entries {
+        return Extracted::NotInspectable(Why::TooLarge);
+    }
+    let mut names = Vec::with_capacity(archive.len());
+    let mut declared: u64 = 0;
+    for i in 0..archive.len() {
+        let Ok(entry) = archive.by_index_raw(i) else {
+            return Extracted::NotInspectable(Why::Damaged);
+        };
+        if entry.encrypted() {
+            return Extracted::NotInspectable(Why::Encrypted);
+        }
+        declared = declared.saturating_add(entry.size());
+        names.push(entry.name().to_string());
+    }
+    if declared > limits.max_unpacked {
+        return Extracted::NotInspectable(Why::TooLarge);
+    }
+    let mut budget = limits.max_unpacked;
+    let mut read =
+        |archive: &mut zip::ZipArchive<Cursor<&[u8]>>, name: &str| -> Result<Vec<u8>, Why> {
+            let entry = archive.by_name(name).map_err(|_| Why::Damaged)?;
+            let mut bytes = Vec::new();
+            // Declared sizes can lie: stop at the budget whatever they say
+            entry
+                .take(budget + 1)
+                .read_to_end(&mut bytes)
+                .map_err(|_| Why::Damaged)?;
+            if bytes.len() as u64 > budget {
+                return Err(Why::TooLarge);
+            }
+            budget -= bytes.len() as u64;
+            Ok(bytes)
+        };
+
+    let has = |name: &str| names.iter().any(|n| n == name);
+    let mut text = String::new();
+    let result: Result<(), Why> = (|| {
+        if has("[Content_Types].xml") {
+            // Office Open XML: the parts that hold what a person wrote
+            let mut shared = Vec::new();
+            if has("xl/sharedStrings.xml") {
+                shared = xml_strings(&read(&mut archive, "xl/sharedStrings.xml")?, "si");
+            }
+            for name in names.iter().filter(|n| ooxml_text_part(n)) {
+                let xml = read(&mut archive, name)?;
+                if name.starts_with("xl/worksheets/") {
+                    xlsx_sheet(&xml, &mut text);
+                } else {
+                    xml_text(&xml, &mut text);
+                }
+                text.push('\n');
+            }
+            text.extend(shared.iter().map(|s| format!("{s}\n")));
+        } else if names.first().is_some_and(|n| n == "mimetype")
+            && read(&mut archive, "mimetype")?.starts_with(b"application/vnd.oasis.opendocument")
+        {
+            // OpenDocument: an encrypted one says so in its manifest
+            if has("META-INF/manifest.xml")
+                && contains(
+                    &read(&mut archive, "META-INF/manifest.xml")?,
+                    b"encryption-data",
+                )
+            {
+                return Err(Why::Encrypted);
+            }
+            for name in ["content.xml", "styles.xml"] {
+                if has(name) {
+                    xml_text(&read(&mut archive, name)?, &mut text);
+                    text.push('\n');
+                }
+            }
+        } else {
+            // An archive: each file inside, one level deep
+            for name in names.iter().filter(|n| !n.ends_with('/')) {
+                let bytes = read(&mut archive, name)?;
+                match extract_at("", Some(name), &bytes, limits, 1) {
+                    Extracted::Text(inner) => {
+                        text.push_str(&inner);
+                        text.push('\n');
+                    }
+                    Extracted::NoText => {}
+                    Extracted::NotInspectable(why) => return Err(why),
+                }
+            }
+        }
+        Ok(())
+    })();
+    match result {
+        Ok(()) => Extracted::Text(text),
+        Err(why) => Extracted::NotInspectable(why),
+    }
+}
+
+fn ooxml_text_part(name: &str) -> bool {
+    let xml = name.ends_with(".xml");
+    xml && (name == "word/document.xml"
+        || [
+            "word/header",
+            "word/footer",
+            "word/footnotes",
+            "word/endnotes",
+            "word/comments",
+        ]
+        .iter()
+        .any(|p| name.starts_with(p))
+        || name.starts_with("xl/worksheets/sheet")
+        || name.starts_with("ppt/slides/slide")
+        || name.starts_with("ppt/notesSlides/"))
+}
+
+fn contains(haystack: &[u8], needle: &[u8]) -> bool {
+    haystack.windows(needle.len()).any(|w| w == needle)
+}
+
+/// The local name of a tag, without its namespace prefix.
+fn local(name: &[u8]) -> &[u8] {
+    name.rsplit(|b| *b == b':').next().unwrap_or(name)
+}
+
+fn push_entity(entity: &[u8], out: &mut String) {
+    match entity {
+        b"lt" => out.push('<'),
+        b"gt" => out.push('>'),
+        b"amp" => out.push('&'),
+        b"apos" => out.push('\''),
+        b"quot" => out.push('"'),
+        _ => {
+            let code = match entity {
+                [b'#', b'x' | b'X', hex @ ..] => std::str::from_utf8(hex)
+                    .ok()
+                    .and_then(|h| u32::from_str_radix(h, 16).ok()),
+                [b'#', dec @ ..] => std::str::from_utf8(dec).ok().and_then(|d| d.parse().ok()),
+                _ => None,
+            };
+            if let Some(c) = code.and_then(char::from_u32) {
+                out.push(c);
+            }
+        }
+    }
+}
+
+/// Every text node, runs joined as written, a new line after each paragraph
+/// or row and a tab after each cell, so a number split across runs is whole
+/// again.
+fn xml_text(xml: &[u8], out: &mut String) {
+    let mut reader = Reader::from_reader(xml);
+    let mut buf = Vec::new();
+    loop {
+        match reader.read_event_into(&mut buf) {
+            Ok(Event::Text(t)) => {
+                if let Ok(text) = t.xml_content(XmlVersion::Implicit1_0) {
+                    out.push_str(&text);
+                }
+            }
+            Ok(Event::CData(t)) => out.push_str(&String::from_utf8_lossy(&t)),
+            Ok(Event::GeneralRef(entity)) => push_entity(&entity, out),
+            Ok(Event::End(e)) => match local(e.name().as_ref()) {
+                b"p" | b"h" | b"tr" | b"row" | b"table-row" | b"br" => out.push('\n'),
+                b"tc" | b"c" | b"table-cell" | b"tab" => out.push('\t'),
+                _ => {}
+            },
+            Ok(Event::Empty(e)) => match local(e.name().as_ref()) {
+                b"br" | b"line-break" => out.push('\n'),
+                b"tab" | b"s" => out.push(' '),
+                _ => {}
+            },
+            Ok(Event::Eof) | Err(_) => break,
+            _ => {}
+        }
+        buf.clear();
+    }
+}
+
+/// The text of each `item` element (a shared string in XLSX).
+fn xml_strings(xml: &[u8], item: &str) -> Vec<String> {
+    let mut reader = Reader::from_reader(xml);
+    let mut buf = Vec::new();
+    let mut items = Vec::new();
+    let mut current: Option<String> = None;
+    loop {
+        match reader.read_event_into(&mut buf) {
+            Ok(Event::Start(e)) if local(e.name().as_ref()) == item.as_bytes() => {
+                current = Some(String::new())
+            }
+            Ok(Event::End(e)) if local(e.name().as_ref()) == item.as_bytes() => {
+                items.extend(current.take());
+            }
+            Ok(Event::Text(t)) => {
+                if let (Some(s), Ok(text)) =
+                    (current.as_mut(), t.xml_content(XmlVersion::Implicit1_0))
+                {
+                    s.push_str(&text);
+                }
+            }
+            Ok(Event::GeneralRef(entity)) => {
+                if let Some(s) = current.as_mut() {
+                    push_entity(&entity, s);
+                }
+            }
+            Ok(Event::Eof) | Err(_) => break,
+            _ => {}
+        }
+        buf.clear();
+    }
+    items
+}
+
+/// A worksheet's cell values: numbers and inline strings. Cells holding a
+/// shared string are skipped here; the shared strings are read whole.
+fn xlsx_sheet(xml: &[u8], out: &mut String) {
+    let mut reader = Reader::from_reader(xml);
+    let mut buf = Vec::new();
+    let mut shared_cell = false;
+    let mut in_value = false;
+    loop {
+        match reader.read_event_into(&mut buf) {
+            Ok(Event::Start(e)) => match local(e.name().as_ref()) {
+                b"c" => {
+                    shared_cell = e
+                        .attributes()
+                        .flatten()
+                        .any(|a| a.key.as_ref() == b"t" && a.value.as_ref() == b"s");
+                }
+                b"v" | b"t" => in_value = true,
+                _ => {}
+            },
+            Ok(Event::End(e)) => match local(e.name().as_ref()) {
+                b"v" | b"t" => in_value = false,
+                b"c" => out.push('\t'),
+                b"row" => out.push('\n'),
+                _ => {}
+            },
+            // A shared string's cell holds only its index: the string itself
+            // is added with the shared strings
+            Ok(Event::Text(t)) if in_value && !shared_cell => {
+                if let Ok(text) = t.xml_content(XmlVersion::Implicit1_0) {
+                    out.push_str(&text);
+                }
+            }
+            Ok(Event::Eof) | Err(_) => break,
+            _ => {}
+        }
+        buf.clear();
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::io::Write;
+    use zip::{ZipWriter, write::SimpleFileOptions};
+
+    fn zip_of(files: &[(&str, &str)]) -> Vec<u8> {
+        let mut zip = ZipWriter::new(Cursor::new(Vec::new()));
+        for (name, body) in files {
+            zip.start_file(*name, SimpleFileOptions::default()).unwrap();
+            zip.write_all(body.as_bytes()).unwrap();
+        }
+        zip.finish().unwrap().into_inner()
+    }
+
+    fn text_of(extracted: Extracted) -> String {
+        match extracted {
+            Extracted::Text(text) => text,
+            other => panic!("expected text, got {other:?}"),
+        }
+    }
+
+    #[test]
+    fn plain_text_and_html() {
+        let limits = Limits::default();
+        assert_eq!(
+            text_of(extract("text/plain", None, b"card 4242", &limits)),
+            "card 4242"
+        );
+        let utf16: Vec<u8> = [0xFF, 0xFE]
+            .into_iter()
+            .chain("héllo".encode_utf16().flat_map(u16::to_le_bytes))
+            .collect();
+        assert_eq!(
+            text_of(extract(
+                "application/octet-stream",
+                Some("a.csv"),
+                &utf16,
+                &limits
+            )),
+            "héllo"
+        );
+        let html = "<html><style>p{}</style><p>Card&nbsp;4242</p><script>x()</script><td>a</td><td>b</td></html>";
+        let text = text_of(extract("text/html", None, html.as_bytes(), &limits));
+        assert!(
+            text.contains("Card 4242") && !text.contains("x()") && !text.contains("p{}"),
+            "{text:?}"
+        );
+        assert_eq!(
+            extract("image/png", Some("a.png"), b"\x89PNG....", &limits),
+            Extracted::NoText
+        );
+    }
+
+    #[test]
+    fn docx_joins_split_runs() {
+        let doc = r#"<w:document xmlns:w="w"><w:body><w:p><w:r><w:t>Card 4242 42</w:t></w:r><w:r><w:t>42 4242 4242</w:t></w:r></w:p><w:p><w:r><w:t>A &amp; B</w:t></w:r></w:p></w:body></w:document>"#;
+        let docx = zip_of(&[
+            ("[Content_Types].xml", "<Types/>"),
+            ("word/document.xml", doc),
+        ]);
+        let text = text_of(extract(
+            "application/vnd.openxmlformats-officedocument.wordprocessingml.document",
+            Some("a.docx"),
+            &docx,
+            &Limits::default(),
+        ));
+        assert!(text.contains("Card 4242 4242 4242 4242\nA & B"), "{text:?}");
+    }
+
+    #[test]
+    fn xlsx_numbers_and_shared_strings() {
+        let sheet = r#"<worksheet><sheetData><row><c r="A1" t="s"><v>0</v></c><c r="B1"><v>4242424242424242</v></c></row></sheetData></worksheet>"#;
+        let shared = r#"<sst><si><t>IBAN GB29 NWBK 6016 1331 9268 19</t></si></sst>"#;
+        let xlsx = zip_of(&[
+            ("[Content_Types].xml", "<Types/>"),
+            ("xl/sharedStrings.xml", shared),
+            ("xl/worksheets/sheet1.xml", sheet),
+        ]);
+        let text = text_of(extract("", Some("book.xlsx"), &xlsx, &Limits::default()));
+        assert!(
+            text.contains("4242424242424242") && text.contains("GB29 NWBK 6016 1331 9268 19"),
+            "{text:?}"
+        );
+        // The shared string's index isn't read as a value
+        assert!(
+            !text.contains("\t0\t") && !text.starts_with('0'),
+            "{text:?}"
+        );
+    }
+
+    #[test]
+    fn opendocument_and_encrypted_opendocument() {
+        let content = r#"<office:document-content xmlns:text="t"><text:p>SSN 078-05-1120</text:p></office:document-content>"#;
+        let odt = zip_of(&[
+            ("mimetype", "application/vnd.oasis.opendocument.text"),
+            ("content.xml", content),
+        ]);
+        assert!(
+            text_of(extract("", Some("a.odt"), &odt, &Limits::default()))
+                .contains("SSN 078-05-1120")
+        );
+        let manifest = r#"<manifest:manifest><manifest:file-entry><manifest:encryption-data/></manifest:file-entry></manifest:manifest>"#;
+        let locked = zip_of(&[
+            ("mimetype", "application/vnd.oasis.opendocument.text"),
+            ("META-INF/manifest.xml", manifest),
+            ("content.xml", "x"),
+        ]);
+        assert_eq!(
+            extract("", Some("a.odt"), &locked, &Limits::default()),
+            Extracted::NotInspectable(Why::Encrypted)
+        );
+    }
+
+    #[test]
+    fn archives() {
+        let limits = Limits::default();
+        let archive = zip_of(&[
+            ("notes/a.txt", "card 4242424242424242"),
+            ("b.png", "\u{89}PNG"),
+        ]);
+        assert!(
+            text_of(extract("application/zip", Some("x.zip"), &archive, &limits))
+                .contains("4242424242424242")
+        );
+        let nested = zip_of(&[(
+            "inner.zip",
+            std::str::from_utf8(&[b'P', b'K', 3, 4]).unwrap(),
+        )]);
+        assert_eq!(
+            extract("application/zip", Some("x.zip"), &nested, &limits),
+            Extracted::NotInspectable(Why::NestedArchive)
+        );
+
+        // Password-protected
+        let mut zip = ZipWriter::new(Cursor::new(Vec::new()));
+        zip.start_file(
+            "secret.txt",
+            SimpleFileOptions::default().with_aes_encryption(zip::AesMode::Aes256, "pw"),
+        )
+        .unwrap();
+        zip.write_all(b"4242424242424242").unwrap();
+        let locked = zip.finish().unwrap().into_inner();
+        assert_eq!(
+            extract("application/zip", Some("x.zip"), &locked, &limits),
+            Extracted::NotInspectable(Why::Encrypted)
+        );
+
+        // Past the limits
+        let small = Limits {
+            max_unpacked: 10,
+            max_entries: 1,
+        };
+        assert_eq!(
+            extract("application/zip", Some("x.zip"), &archive, &small),
+            Extracted::NotInspectable(Why::TooLarge)
+        );
+        assert_eq!(
+            extract("application/zip", None, b"PK\x03\x04garbage", &limits),
+            Extracted::NotInspectable(Why::Damaged)
+        );
+    }
+
+    #[test]
+    fn not_inspectable_kinds() {
+        let limits = Limits::default();
+        assert_eq!(
+            extract("application/octet-stream", None, b"%PDF-1.7 ...", &limits),
+            Extracted::NotInspectable(Why::Pdf)
+        );
+        let mut ole = OLE_MAGIC.to_vec();
+        ole.extend(std::iter::repeat_n(0, 64));
+        assert_eq!(
+            extract("", Some("old.doc"), &ole, &limits),
+            Extracted::NotInspectable(Why::LegacyOffice)
+        );
+        ole.extend("EncryptedPackage".encode_utf16().flat_map(u16::to_le_bytes));
+        assert_eq!(
+            extract("", Some("new.docx"), &ole, &limits),
+            Extracted::NotInspectable(Why::Encrypted)
+        );
+    }
+}
diff --git a/crates/features/src/mailflow/mod.rs b/crates/features/src/mailflow/mod.rs
new file mode 100644
index 0000000..d218aac
--- /dev/null
+++ b/crates/features/src/mailflow/mod.rs
@@ -0,0 +1,23 @@
+/*
+ * SPDX-FileCopyrightText: 2026 Coffey Labs
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+//! Data loss prevention and mail flow rules (dlp-and-mail-flow-rules spec).
+//!
+//! Pure functions over text and attachment bytes, so everything here is
+//! unit-tested without a server:
+//!
+//! - [`detectors`]: find identifiers in text (payment cards, IBANs,
+//!   national ID numbers, keys), each by its published format and check
+//!   (§2.3);
+//! - [`words`]: an organization's own word lists and patterns;
+//! - [`extract`]: the text of an attachment, or why it can't be read.
+//!
+//! Nothing here writes what it finds anywhere: callers get counts, and the
+//! matched text never leaves the evaluation (§2.7).
+
+pub mod detectors;
+pub mod extract;
+pub mod words;
diff --git a/crates/features/src/mailflow/words.rs b/crates/features/src/mailflow/words.rs
new file mode 100644
index 0000000..e171ff2
--- /dev/null
+++ b/crates/features/src/mailflow/words.rs
@@ -0,0 +1,109 @@
+/*
+ * SPDX-FileCopyrightText: 2026 Coffey Labs
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+//! An organization's own word lists and patterns (§2.3). Both count
+//! occurrences, not distinct values: "confidential" three times is three.
+
+use aho_corasick::{AhoCorasick, AhoCorasickBuilder, MatchKind};
+use regex::{Regex, RegexBuilder};
+
+/// How large a compiled pattern may grow. Keeps a rule someone writes from
+/// making every message slow to send.
+const PATTERN_SIZE_LIMIT: usize = 1 << 20;
+
+/// Words and phrases, matched whole and ignoring case.
+#[derive(Debug, Clone)]
+pub struct WordList {
+    matcher: AhoCorasick,
+}
+
+impl WordList {
+    /// Builds a list from words or phrases; empty entries are skipped.
+    pub fn new<I, S>(words: I) -> Result<Self, String>
+    where
+        I: IntoIterator<Item = S>,
+        S: AsRef<str>,
+    {
+        let words: Vec<String> = words
+            .into_iter()
+            .map(|w| w.as_ref().trim().to_lowercase())
+            .filter(|w| !w.is_empty())
+            .collect();
+        if words.is_empty() {
+            return Err("The list has no words".into());
+        }
+        AhoCorasickBuilder::new()
+            .match_kind(MatchKind::LeftmostLongest)
+            .build(&words)
+            .map(|matcher| Self { matcher })
+            .map_err(|err| err.to_string())
+    }
+
+    /// How many times any word of the list appears in `text`.
+    pub fn count(&self, text: &str) -> usize {
+        let text = text.to_lowercase();
+        self.matcher
+            .find_iter(&text)
+            .filter(|m| super::detectors::stands_alone(&text, m.start(), m.end()))
+            .count()
+    }
+}
+
+/// An organization's regular expression.
+#[derive(Debug, Clone)]
+pub struct Pattern {
+    regex: Regex,
+}
+
+impl Pattern {
+    /// Compiles `pattern`, or says why it can't be used. Matching ignores
+    /// case unless the pattern turns that off with `(?-i)`.
+    pub fn new(pattern: &str) -> Result<Self, String> {
+        RegexBuilder::new(pattern)
+            .case_insensitive(true)
+            .size_limit(PATTERN_SIZE_LIMIT)
+            .build()
+            .map(|regex| Self { regex })
+            .map_err(|err| err.to_string())
+    }
+
+    /// How many times the pattern matches in `text`.
+    pub fn count(&self, text: &str) -> usize {
+        self.regex.find_iter(text).filter(|m| !m.is_empty()).count()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn words_whole_and_any_case() {
+        let list = WordList::new(["Project Falcon", "confidential", " "]).unwrap();
+        assert_eq!(
+            list.count(
+                "CONFIDENTIAL: project falcon notes. Not confidentiality, not projectfalcon."
+            ),
+            2
+        );
+        assert_eq!(list.count("Confidential, confidential and confidential"), 3);
+        // Non-ASCII case folding
+        let list = WordList::new(["GEHEIM", "Straße"]).unwrap();
+        assert_eq!(list.count("streng geheim, STRASSE ist nicht Straße"), 2);
+        assert!(WordList::new(["", "  "]).is_err());
+    }
+
+    #[test]
+    fn patterns() {
+        let pattern = Pattern::new(r"\bPRJ-\d{4}\b").unwrap();
+        assert_eq!(pattern.count("prj-1234 and PRJ-5678, not PRJ-12"), 2);
+        assert!(Pattern::new("(unclosed").is_err());
+        // Too large to compile within the limit
+        assert!(Pattern::new(r"\w{1000}\w{1000}\w{1000}").is_err());
+        // Empty matches don't count
+        assert_eq!(Pattern::new("x*").unwrap().count("abc"), 0);
+    }
+}