I am quite curious about the circumstances of this question. I was not aware that Dovecot actually offered mail submission service. If Dovecot does offer such a service, then it will have to relay the submitted mail to the real MTA, which is very likely not Dovecot. At the moment I have Postfix set up as MTA for that purpose —
Relaying on port 25 is usually quick and easy to whitelist for certain permitted hosts, but otherwise port 587, optionally with STARTTLS, and/or port 465 with SSL/TLS is generally set up for user authenticated mail submissions.
See also: https://www.mailgun.com/blog/which-smtp-port-understanding-ports-25-465-587/
On July 28, 2021 6:10:28 AM AKDT, Dan Conway <darkc0de@archnix6.net> wrote:
Hello,
Is it possible to disable the requirement for authentication on the submission service? I'm trying to require authentication for all, except for a handful of IP addresses.
Thank you.
ehlo test.com 250-aaa 250-AUTH PLAIN LOGIN 250-BURL imap 250-CHUNKING 250-DSN 250-ENHANCEDSTATUSCODES 250-SIZE 250 PIPELINING MAIL FROM:<test@test.com> 530 5.7.0 Authentication required.
-- Sent from my Android device with K-9 Mail. Please excuse my brevity.