On Thu, 26 Mar 2026 12:03:48 +0100
Patrick Ben Koetter via Postfix-users <[email protected]> wrote:
There's no AUTH. Your server also should not show AUTH.
On 26.03.26 12:16, Sad Clouds via Postfix-users wrote:
It looks like there is no AUTH, but for some reason I can still submit
mail on port 25 in some cases. There are two cases I'm testing:
1. When sending from [email protected] to [email protected] and this
domain is in virtual_mailbox_domains, then MUA submission on port 25 is
permitted. Is this normal and is there a way to disable submission
completely for port 25 and only use this port for mail relay?
2. When sending from @example.com to @gmail.com, then MUA submission
fails with "relay access denied". So in this context, does "relay"
refer to submission and how does Postfix differentiate between MTAs and
MUAs? I want to stop MUAs from using port 25 completely, since I have
different set of options and restrictions for submission.
This way, you are sending mail TO the server, not submitting mail.
When your server is the final destination, it can hardly differ between
remote mail servers sending mail to you and mail user agents doing the same.
You can block end users' machines from submitting mail on port 25 by
blocking them from connecting to port 25 anywhere, perhaps on your company's
firewall.
I recommend doing this as it stops your users from spamming remote sites,
should their computers getting infected or taken over by abusers.
--
Matus UHLAR - fantomas, [email protected] ; http://www.fantomas.sk/
Warning: I wish NOT to receive e-mail advertising to this address.
Varovanie: na tuto adresu chcem NEDOSTAVAT akukolvek reklamnu postu.
I don't have lysdexia. The Dog wouldn't allow that.
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