base-trixie: the image on Debian trixie, Postfix 3.10.13; Received: hidden on 465/587

The runtime base is debian:trixie-slim, the build stage golang:1.26-trixie:
Postfix 3.10.13 with upstream's 2026 security fixes up to the August
batch, libmilter 8.18.1, OpenSSL 3.5. Every citation of another program in
code, scripts and documents was re-read against the trixie sources
(dev/upstream; bookworm's kept in dev/upstream-bookworm) and updated;
development.md's cited-package table holds the trixie versions.

What the re-reading changed in behaviour:
- logtail: reject lines with sasl_method/sasl_username/sasl_sender
  (smtpd_check.c:1019-1026); cleanup's "removed (canceled)" forgets a
  port-25 id (cleanup_api.c:363-364).
- internal/postfix/retry.go reads postconf's stdout only: since 3.9 a
  deprecated-parameter warning on stderr made one value too many and the
  panel fell back to the compiled-in retry policy.
- logrotate-loop.sh: logrotate 3.22 exits 1 when it ignores a config;
  the loop refuses on that output whatever the status.
- postfix-config.sh: cyrus_sasl_config_path set explicitly (bookworm's
  07_sasl_config.diff is gone); maillog_file_permissions=0640; mynetworks
  explicit; Dockerfile: SYNC_CHROOT= in /etc/default/postfix,
  opendkim-tools dropped, openssl named, systemd-standalone-sysusers so
  cron does not bring the whole of systemd.
- The selfpost group is 10998, outside the system range 100-999: in
  trixie a package took 998 and the build failed (owner's decision:
  a conflict-free id, the distribution's own ids untouched). The
  entrypoint hands /data back by name when the user or the group differs.
  Guide, backup refusal text, help (design commit 68ec8b2), e2e.
- smtpd_hide_client_session=yes on smtps and submission (owner's
  decision): Received: names no client, TLS, login or protocol; port 25
  keeps the full header. e2e checks both.
- test/upstream/opendkim-probe.sh makes keys with openssl genrsa.

Tests: on the server, make e2e exit 0 (674 s, the image built on trixie),
go vet + go test 27 packages ok. CHANGELOG [Unreleased], guide,
architecture.md, security.md, roadmap.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/logtail/refusals_test.go

@@ -31,8 +31,9 @@ func (r *refusalProbe) AttachRefusalLine(clientIP, login, from string, _ time.Ti
 
 // The mail.log lines in this file are composed by hand, with the e2e stand's
 // names and addresses (smtpd.c check_milter_reply(), mail_open_stream();
-// cleanup_milter.c cleanup_milter_apply(), Postfix 3.7.11), with the stamp
-// Postfix 3.7 writes (src/util/msg_logger.c, "%b %d %H:%M:%S").
+// smtpd_check.c log_whatsup(); cleanup_milter.c cleanup_milter_apply(),
+// Postfix 3.10.13), with the stamp Postfix 3.10 writes
+// (src/util/msg_logger.c, "%b %d %H:%M:%S").
 //
 // The NOQUEUE line of a refusal at MAIL FROM goes on its row; a line whose
 // row is not written yet waits and is tried again; port 25's and other
@@ -45,7 +46,7 @@ func TestRefusalLines(t *testing.T) {
 	for _, other := range []string{
 		`Oct 14 12:00:00 mail postfix/inbound/smtpd[372]: NOQUEUE: milter-reject: MAIL from unknown[203.0.113.7]: 451 4.7.1 Service unavailable - try again later; from=<a@stranger.example> proto=ESMTP helo=<x>`,
 		`Oct 14 12:00:00 mail postfix/smtpd[11]: NOQUEUE: milter-reject: CONNECT from unknown[10.77.0.1]: 451 4.7.1 Service unavailable - try again later; proto=SMTP`,
-		`Oct 14 12:00:00 mail postfix/smtpd[11]: NOQUEUE: reject: RCPT from unknown[10.77.0.1]: 553 5.7.1 <a@x>: Sender address rejected: not owned by user app1; from=<a@x> to=<b@y> proto=ESMTP helo=<x>`,
+		`Oct 14 12:00:00 mail postfix/smtpd[11]: NOQUEUE: reject: RCPT from unknown[10.77.0.1]: 553 5.7.1 <a@x>: Sender address rejected: not owned by user app1; from=<a@x> to=<b@y> proto=ESMTP helo=<x> sasl_method=PLAIN sasl_username=app1`,
 		// No login: no application's refusal (the panel down refuses every
 		// session, an unauthenticated one too).
 		`Oct 14 12:00:00 mail postfix/smtpd[12]: NOQUEUE: milter-reject: MAIL from unknown[10.77.0.1]: 451 4.7.1 Service unavailable - try again later; from=<billing@sender.e2e.test> proto=ESMTP helo=<x>`,