First of all, thanks for the multiple and detailed repsonses with error
reports.
Indeed, this is the missing link and we obviously underestimated the
reachability problem we have here on our DNS service.
We already set up a plan to fix the issue and are looking forward
getting this solved.
Thanks again and cheers
Michael
Am 12.12.2023 um 10:56 schrieb Tobias Herkula via mailop:
This seems to be an issue on your site, I checked the logs and all the times we were not
able to deliver mails to you the error we had was "temporary mx resolver error".
Most likely root cause: "dns.hiskp.uni-bonn.de." does not answer queries via
UDP, as you also have a couple of more systems answering fine, this would also explain
why it sometimes works and sometimes not.
/ Tobias Herkula
Senior Product Owner Mail Security
Product Management Mail Transfer & Mail Security
1&1 Mail & Media GmbH
Hauptsitz Montabaur, Amtsgericht Montabaur, HRB 7666
Geschäftsführer: Alexander Charles, Dana Kraft, Thomas Ludwig, Dr. Michael
Hagenau
Member of United Internet
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-Original Message-
From: mailop On Behalf Of Michael Lang via mailop
Sent: Tuesday, December 12, 2023 8:50 AM
To: mailop@mailop.org
Subject: [mailop] "451 Requested action aborted: local error in processing"
when submitting email to ionos email services.
Hi everybody,
for approximately one year, we are receiving regular complaints from remote
contacts having problems to ship email from a service like gmx.de, gmx.net,
1und1.de and similar in fact services hosted by ionos to our email domain
(@hiskp.uni-bonn.de, MX=mx8.hiskp.uni-bonn.de).
During submission of ionos customers to one of the ionos servers people
eventually receive an error of type:
451 Requested action aborted: local error in processing
We tried to track this error on our own and found out that this warning
randomly appears and if a resubmit is tried a few seconds later, submission via
ionos services works flawlessly. Guessing that this might be caused by the MX
entry for our destination getting lost in the cache of ionos submission servers
due to a to short TTL, we tried changing that in our DNS, but this did not
change the scenario.
We furthermore observed that mail systems obviously receiving heavier load than
we do seem not to have this problem or it occurs very rarely.
Anyway that is for now a wild guess from us.
To us this appears as if the timeout checking DNS for the MX + A / records
is too short, independant ot the TTL and it furthermore appears to be load
dependant on the ionos servers.
The same phaenomenon we regularly observe when mail from our site is shipped to
ionos servers. Here emails regularly get deferred for several seconds with the
same 451 error but are successfully acepted with code
250 a few seconds later.
As access to intermediate and top layer domain servers is obviously beyond our
administrational range, does anybody have an idea why this occurs really? Is
there maybe a contact at ionos to subscribe our email service for flawless
transport, such as e.g. at t-online.de? Is this problem known to anybody else
and what did you do to fight it?
With kind regards
Michael
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URL;TYPE=work:https://www.hiskp.uni-bonn.de
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