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/main_test.go

@@ -386,6 +386,9 @@ func TestE2E(t *testing.T) {
 	run("inbound_relay_delivers_and_refuses", func(t *testing.T) {
 		testInboundRelay(t, sc)
 	})
+	run("inbound_bare_newline_is_one_message", func(t *testing.T) {
+		testInboundBareNewline(t, sc)
+	})
 }
 
 // trimZoneSuffix strips the "e2e.test" suffix a fully-qualified DKIM record