port 25 ends DATA only at CRLF.CRLF: smtpd_forbid_bare_newline=normalize (port25-bare-newline)

Postfix 3.7.11 leaves its 2023 SMTP-smuggling defence off (default "no"
before 3.9, src/smtpd/smtpd.c:807), and the inbound relay's smtp/inet
listener did not turn it on: a "." line ended by a bare LF ended DATA and
what followed was read as the next transaction. The listener now sets
normalize (bare_lf_mask_table, smtpd.c:1656; the DATA loop drops such a
"." line, 3649-3652), the setting Postfix recommends and 3.9's default.
The submission ports keep the default (own-mta-builds, section 5).

Tests: e2e inbound_bare_newline_is_one_message sends the smuggling
sequence over raw SMTP (net/smtp's DotWriter would rewrite the bare LF)
and finds one message at the upstream with the smuggled part inside;
port25 config check asserts the parameter on smtp/inet. On the server:
make e2e exit 0 (511 s), go vet + go test 27 packages ok.

Docs: CHANGELOG [Unreleased] Security, security.md, architecture.md,
guide.md; roadmap: port25-bare-newline, base-trixie and
panel-dkim-signing agreed by the owner in this order.

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

test/e2e/port25_config_check.go

@@ -51,6 +51,9 @@ var port25Cases = []port25Case{
 			// The log tailer tells this listener's refusals from the
 			// submission ports' by the name they are logged under.
 			{param: "syslog_name", contains: "postfix/inbound", wantExact: true},
+			// The SMTP-smuggling defence, off by default on this Postfix
+			// (own-mta-builds, § 5); testInboundBareNewline drives it.
+			{param: "smtpd_forbid_bare_newline", contains: "normalize", wantExact: true},
 			// No antispam milter configured: the inbound journal milter
 			// alone. The submission chain (strict OpenDKIM + journal-milter)
 			// must not reach inbound mail.