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>

internal/web/view/help.go

@@ -40,6 +40,7 @@ const (
 	HelpChecks      = "checks"
 	HelpCertificate = "certificate"
 	HelpRDNS        = "rdns"
+	HelpTestMessage = "test-message"
 	// Outbound
 	HelpDNS  = "dns"
 	HelpApps = "apps"
@@ -99,6 +100,7 @@ func NewHelp(m Meta, inbound bool) *Help {
 		add("Overview", overviewTopics, []MenuItem{
 			{Label: "Health checks", Icon: "ti-activity-heartbeat", Href: "#" + HelpChecks},
 			{Label: "TLS certificate", Icon: "ti-certificate", Href: "#" + HelpCertificate},
+			{Label: "Test message", Icon: "ti-send", Href: "#" + HelpTestMessage},
 			{Label: "Reverse DNS", Icon: "ti-arrows-exchange", Href: "#" + HelpRDNS},
 		})
 	}
@@ -153,6 +155,10 @@ var overviewTopics = []HelpTopic{
 		Rich("The certificate Postfix presents on 465 and 587. The reverse proxy or the image mounts it, the panel does not issue it. Postfix serves its own copy of the mounted file and looks for a renewed one once a day by default; until it takes one up, the card shows it as a renewal waiting, and warns once it has waited longer than that check allows - the container log's cert-reload lines say why. It warns 14 days before expiry unless a renewal is already waiting, and fails once expired, or when the file is missing or unreadable — clients that verify certificates then refuse to connect. It also fails when none of its names is the hostname (",
 			Code("SELFPOST_HOSTNAME"), ") - the tag beside ", Em("Names"), " says which: a client that verifies the name refuses it however valid it is."),
 	}},
+	{ID: HelpTestMessage, Title: "Test message", Body: []Text{
+		Rich("A message from ", Code("postmaster@"), " the server's hostname to one address you type, sent the way notifications are: through Postfix, signed with the DKIM key of the server's own name. It proves the path from this server - TLS, its address's reputation, the SPF and DKIM records of its name - not your domains', which only mail from an application does. The page that opens is its row in the Outbound log: it shows whether the receiving server took it, put it off or refused it, with the lines of ",
+			Code("mail.log"), ". Whether it then reached the inbox or the spam folder only the mailbox can say. The global role sends it, at most ten an hour."),
+	}},
 	{ID: HelpRDNS, Title: "Hostname and reverse DNS", Body: []Text{
 		Rich("The hostname (", Code("SELFPOST_HOSTNAME"), ") must resolve to this server's address, and that address must resolve back to the hostname. Large receivers reject or spam-folder mail from hosts where the two disagree. The PTR record is set at your hosting provider, not in your DNS zone. ",
 			Em("Greeting"), " is the line Postfix opens every connection with, ", Code("220"), " and its banner; it must name the hostname too - a receiver compares it with the name it looked up - and a container id or ",