docs-audit: the guide and the panel's words against the code

The owner's "проверь, что документация актуальна с кодом" (2026-10-16);
design c5edbd8 and f1cc3f3 settled which side moves.

The panel follows its mockups: an inbound domain's MX box ends with
"Checked N ago" (dnscheck.InboundMXCheckedAt, from the cache) and its side
menu has See also › Log for this domain (the Inbound log, filtered); a
deferred message's history ends with the open dot of the wait in the
queue, the lifetime from this Postfix; Health's lead says six cards;
Overview's head says it refreshes on its own; DMARC's hint for an
unaligned third party is the mockup's sentence.

Help, word for word with the mockup and true to the code: the
application's password kept by the server (sasldb2) for an export, a
From:/Sender: refusal one row of the Outbound log, every backup password
check counted (AllowPasswordChange before the compare), a password set
for another user ends all their sessions, the limit mail daily per
sending domain. The Filter lists topic and its menu entry are no longer
shown to a domain administrator: their page is 404 to one
(requireInboundGlobal), and Help shows only what its viewer can open.

guide.md: Health's readings in the order of the boxes, with Notification
mail; the menu and role tables have the Inbound log and Filter lists; port
25's chain has the inbound journal; level 2 does not depend on the client
address, the client list refuses a message without one; four kinds of
refusal (wrong Sender); the log is filtered, not searched, and a message
is traced by its row; a bounced row shows only the queue lifetime;
TRUSTED_PROXY_CIDR serves sign-in and setup, the account-change limit is
per user; notifications' first check and hourly ceiling. The Apache
vhost's comment names mod_rewrite.

Tests: TestHelpHasTheInboundLogAndFilterListsTopics (the topic per
viewer), TestDeliveryPageDeferredUsesRetryPolicy (the wait),
TestInDomainShowsTheMockupsBoxes (checked, the log link), the Overview
head; the DMARC tests take the new hint. go vet + go test (26 packages)
and make e2e on the test server for this tree.

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

internal/dnscheck/dnscheck.go

@@ -264,6 +264,19 @@ func (c *Checker) InboundMX(name, hostname string, force bool) Result {
 	return result
 }
 
+// InboundMXCheckedAt is when the MX of name was last looked up for
+// hostname, zero when it has not been: the cache is filled when it is, and
+// keeps the result domainTTL.
+func (c *Checker) InboundMXCheckedAt(name, hostname string) time.Time {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	entry, ok := c.inbound[name+"\x00"+hostname]
+	if !ok {
+		return time.Time{}
+	}
+	return entry.expires.Add(-c.domainTTL)
+}
+
 func (c *Checker) checkInboundMX(ctx context.Context, name, hostname string) Result {
 	mxs, err := c.resolver.LookupMX(ctx, name)
 	if err != nil {