test-email: a test message from Server › Health

Decided by the owner on 2026-10-13 (out of preflight); the sender is his
choice of 2026-10-16 ("Да, адрес годится"); mockups e92769f, e3b2501,
8f0ccf9, the route guard 75f97c9.

Card 09 on Health, in the right stack's static end (the left stack is
polled whole): one recipient and Send. HandleTestMessage (global role)
takes one address (validate.AccountEmail - no list, nothing that reads as
an option), at most ten an hour counted from the send log, writes the
message's send-log row first (store.InsertTestMessage: queued, the
hostname as domain, no application, no queue id), awaits its Message-ID
(logtail.AwaitMessageID) and hands it to sendmail as notifications go
(notify.Mailer.SendWithID: postmaster@ the hostname, signed by the local
socket with the key of the server's own name). The browser lands on the
row; the tailer gives it its queue id from cleanup's message-id= line
(src/cleanup/cleanup_message.c:639) and from then on its delivery lines
its status. Postfix refusing the hand-over removes the row; sendmail out
of time keeps it (postdrop may have queued it). The sweep closes a row
whose id was never seen once it is no longer awaited
(CloseUnmatchedTestMessages); an id awaited past ten minutes is not taken.

Reviewed for security before the commit (2026-10-17): no high or medium;
its three low findings are fixed in this commit (the unmatched row's
close, the awaited id's age, the timeout keeping the row) and the
security.md bullet says how the queue id is matched.

Tests: TestTestMessage (refusals, the row and the page, Postfix refusing,
the hourly ten), TestTestMessageTimeoutKeepsTheRow, TestTestMessageRows,
TestCloseUnmatchedTestMessages, TestAwaitedMessageID,
TestRunGivesTheTestMessageItsQueueID, TestHealthTestMessageCard; e2e sends
one to the sink: the row is sent with a long queue id, the sink has it
signed d=mail.e2e.test. go vet + go test (26 packages) and make e2e on the
test server for this tree.

Docs: help (word for word with the mockup), guide § Overview and Health,
architecture § Log tailer, security.md, CHANGELOG [Unreleased] § Added,
roadmap row done.

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

docs/architecture.md

@@ -590,6 +590,19 @@ inbound journal's. The tail of a line is the far end's words (a reply, a HELO
 name), and a pattern that could start there let a stranger's HELO name file a
 delivery (audit 2026-10-12, M12).
 
+**The test message** (test-email, `2.12.0`) is the one row the panel writes
+itself: Server › Health hands it to `sendmail(1)`, which tells nothing of the
+queue id, and the journal-milter does not see local mail. The row is written
+first, queued and with no queue id, and its Message-ID is awaited
+(`logtail.AwaitMessageID`, in memory, ten minutes); cleanup's line
+`<id>: message-id=<…>` (Postfix 3.10.13, `src/cleanup/cleanup_message.c:639`)
+gives the row its queue id, and from then on its delivery lines update it as
+any row's. A restart in the second between leaves it without one, and the
+reconcile sweep closes it once the id is no longer awaited
+(`CloseUnmatchedTestMessages`); an id awaited longer than that is not taken
+any more. sendmail out of time keeps the row and the id - postdrop may have
+queued the message all the same.
+
 **The upstream's answer** on the inbound journal (inbound-upstream-result,
 `2.10.0`). Mail accepted on port 25 is handed to its upstream by the same
 `smtp` client as outbound mail, and its delivery lines look alike; what tells