The second lock. While legacy mail protocols are off, a sign-in over IMAP,
POP3, ManageSieve or SMTP AUTH is refused for every account, so a listener
that exists by mistake -- or submission, which the SMTP lock keeps open --
still lets nobody in.
The check sits at the top of each protocol's sign-in, before the
credentials are looked at. So the answer is the same for a right password,
a wrong one and an account that doesn't exist; it isn't auth.failed, so it
counts nothing against the account and never feeds the auto-ban; and the
session stays open, since the mail app is being told, not thrown off.
Mail apps read the spec's words (LP-12, at server scope):
IMAP NO [ALERT] This server allows only INBUXA webmail and JMAP
apps. This mail app can't sign in.
POP3 -ERR [AUTH] ...the same...
ManageSieve NO "This server allows only INBUXA webmail and JMAP apps."
SMTP 535 5.7.0 This server allows only INBUXA webmail and JMAP
apps. This mail app can't send.
SMTP AUTH is refused on every SMTP listener, port 25 included: only mail
apps authenticate, so inbound delivery is untouched. LMTP is left alone.
The policy is read from the store on each sign-in rather than cached, so
every node of a cluster answers the same the moment the switch turns.
Each refusal raises a new event, auth.legacy-protocol-refused (id 642, info
level, also in the packaged schema), with the protocol as source, the
policy's scope and the domain -- never the account. The session adds the
listener and remote IP.
tests/e2e/legacy_protocols.py now also proves, on a running server: a
normal IMAP and submission sign-in works with the switch on, before and
after; while off, submission refuses the right password and six wrong ones
with the same words and without hanging up; and an IMAP listener created by
mistake while off refuses the right password, a wrong one and an account
that doesn't exist. All 33 checks pass. SMTP sign-ins in the script wait
out a second first: every connection arrives from Docker's gateway, and the
stock inbound throttle takes five a second from one IP.
jcoffey-dev
04252000da