PGNet Dev wrote:
> legitsen...@example.com
>
> my postfix instance does what I intend, and 'rejects' ...
I assume this is due to use of reject_unknown_sender_domain in which
case unknown_address_reject_code applies.
http://www.postfix.org/postconf.5.html#unknown_address_reject_code
> 2020-10-28T13:15:23.753811-07:00 svr017
> postfix/postscreen-internal/smtpd[24098]: NOQUEUE: reject: RCPT from
> smtp.clearbearing.net[64.25.214.9]: 450 4.1.8 <legitsen...@example.con>:
> Sender address rejected: Domain not found; from=<legitsen...@example.con>
> to=<m...@mydomain.com> proto=ESMTP helo=<obermeyer.clearbearing.net>
Looks perfectly normal. This is not a problem. This is the normal
way things are supposed to work. It will retry for 3-5 days and then
expire the message. It's normal.
> the issue i'm trying to solve is that the server on their end keeps
> resending the reject-ed msg every 5 mins. been going on for days.
Usually this will go on for 3-5 days as that is the normal amount of
time for sending MTAs to keep retrying undeliverable mail. That's the
normal behavior. At least 3 days to bridge over a weekend until
someone can return to fix a problem. Because failures always happen
late Friday night after the admin has already gone home for the
weekend. And 5 days because sometimes Monday is a holiday and Tuesday
is so overworked that things don't get fixed until Wednesday. I
shorten the time to 3 days but 5 has been a traditional retry
expiration setting.
The reason why it needs to retry is that this relies upon DNS to
resolve the sender domain. And DNS may have a variety of temporary
failures. Something as simple as a backbone router being overloaded
might cause a transient glitch. Therefore at any given moment a
single failure should not cause the message to be hard rejected.
Doing so will lead to loss of mail.
> the sender themselves can't cure it.
Most users could not do anything about it. The sending site admins
could manually review all mail that is queued and retrying and
manually delete messages that can't ever be delivered. But there is
no good way to automatically do this. And no one is going to manually
review all of this mail.
Instead we all let the standard control flow operate as it was
designed to operate, let it retry for 3-5 days, let it generate a
bounce message back to the sender when it expires. And if it can't
return it to the sender then the MAILER-DAEMON will discard it at that
time.
> their provider, 'clearbearing' has been repeatedly notified
> @support, asking for them to clear their queue of this message, and
> to fix their resend timings; so far no response/action. i'll deal
> with them separately.
I don't understand why this is a problem for you? Since this is the
way things have been designed to work?
> my inclination is to say the heck with it, let it spew endlessly,
> and let postscreen do its job ...
That is the right answer. Let the machine do the work.
> but I am interested in the narrow-case exception handling.
If this really annoys you that you really wanted to take manual action
you could temporarily configure your system to accept mail for the
mispelled example.con and then remove it after it has been accepted
and delivered. If it were me I might add it to Postfix's /etc/hosts
in the chroot jail so that it would accept that misspelling. Then
remove it after it had been delivered.
Bob
