MTA: Log when messages are rejected or discarded by the spam classifier.

CHANGELOG.md

@@ -68,6 +68,7 @@ If you are upgrading from v0.16.x, replace the binary (or run `docker pull`). If
    - Yandex Cloud DNS
 - DNS updater: Log DNS record types and values.
 - Sieve: Allow User Sieve scripts to access `orcpt`.
+- MTA: Log when messages are rejected or discarded by the spam classifier.
 
 ## Changed
 - Bump JMAP File Storage to [draft-ietf-jmap-filenode-14](https://datatracker.ietf.org/doc/html/draft-ietf-jmap-filenode-14).
@@ -85,6 +86,7 @@ If you are upgrading from v0.16.x, replace the binary (or run `docker pull`). If
 - Allow internal TLDs in e-mail addresses.
 - Websocket: Perform case insensitive matching during upgrade.
 - LDAP: Synchronize accounts when expanding mailing list recipients.
+- Sieve: `replace` action adds an extra `From` header.
 
 ## [0.16.5] - 2026-05-11
 

crates/smtp/src/inbound/data.rs

@@ -44,7 +44,7 @@ use std::{
     borrow::Cow,
     time::{Instant, SystemTime},
 };
-use trc::SmtpEvent;
+use trc::{SmtpEvent, SpamEvent};
 use utils::DomainPart;
 
 impl<T: SessionStream> Session<T> {
@@ -453,10 +453,24 @@ impl<T: SessionStream> Session<T> {
                     }
                 }
                 SpamFilterAction::Discard => {
+                    trc::event!(
+                        Spam(SpamEvent::Classify),
+                        SpanId = self.data.session_id,
+                        Result = "discard",
+                        Reason = "Message discarded due to excessive spam score.",
+                    );
+
                     self.data.messages_sent += 1;
                     return (b"250 2.0.0 Message queued for delivery.\r\n"[..]).into();
                 }
                 SpamFilterAction::Reject => {
+                    trc::event!(
+                        Spam(SpamEvent::Classify),
+                        SpanId = self.data.session_id,
+                        Result = "reject",
+                        Reason = "Message rejected due to excessive spam score.",
+                    );
+
                     self.data.messages_sent += 1;
                     return (b"550 5.7.1 Message rejected due to excessive spam score.\r\n"[..])
                         .into();