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>

test/e2e/sender_check_test.go

@@ -53,7 +53,7 @@ func testSenderCheck(t *testing.T, sc *scenario) {
 		{"the listed address with an extension, in envelope and header", who{listLogin, listPassword, "billing+march@" + senderDomain}, "billing+march@" + senderDomain, true},
 		// What a mail library does with a long display name: the line is
 		// folded, and Postfix hands the milter both of its lines (Postfix
-		// 3.7.11, src/milter/milter8.c, milter8_header(): the value is the
+		// 3.10.13, src/milter/milter8.c, milter8_header(): the value is the
 		// whole header as cleanup's MIME state machine collected it,
 		// continuation line included).
 		{"a long name, folded onto a second line", wildcard, "\"The Shop, its orders and its returns desk\"\r\n <orders@" + senderDomain + ">", true},
@@ -112,7 +112,7 @@ func testSenderCheck(t *testing.T, sc *scenario) {
 
 	// What the header case above holds to: Postfix itself refuses the
 	// wildcard application billing@ as envelope sender, at RCPT, because the
-	// address's own key names app-list only (Postfix 3.7.11,
+	// address's own key names app-list only (Postfix 3.10.13,
 	// src/smtpd/smtpd_check.c, reject_auth_sender_login_mismatch(): "553
 	// 5.7.1 <%s>: Sender address rejected: not owned by user %s").
 	if res := attemptSend(sendAttempt{
@@ -250,7 +250,7 @@ func senderCheckDeferredToday(sc *scenario) (int, error) {
 // message is deferred, and the count on Health sees it. Past the DATA
 // command Postfix's cleanup, not smtpd, talks to the milters, so the warning
 // that names the socket is cleanup's (audit 2026-10-12, M13: the counter read
-// smtpd's lines only; Postfix 3.7.11, src/smtpd/smtpd.c, milter_send() to
+// smtpd's lines only; Postfix 3.10.13, src/smtpd/smtpd.c, milter_send() to
 // cleanup, src/cleanup/cleanup_milter.c). The panel is frozen with SIGSTOP
 // once DATA is answered, and thawed after the client has its reply.
 func testPanelHungMidMessage(t *testing.T, sc *scenario) {