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 processingWe 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 / AAAA 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
BEGIN:VCARD VERSION:4.0 EMAIL;PREF=1:[email protected] FN:Michael Lang ORG:Helmholtz-Institut für Strahlen- und Kernphysik\, Rheinische Friedrich- Wilhelms-Universität Bonn;CBELSA/TAPS Hardware Coordinator / HISKP IT Coord inator TITLE:Dr. N:Lang;Michael;;; ADR:;;Nußallee 14-16;Bonn;Nordrhein-Westfalen;53115;Bundesrepublik Deutschl and TEL;TYPE=work;VALUE=TEXT:+49 228 73 2522 TEL;TYPE=fax;VALUE=TEXT:+49 228 73 2505 URL;TYPE=work;VALUE=URL:https://www.hiskp.uni-bonn.de X-MOZILLA-HTML;VALUE=BOOLEAN:FALSE UID:dc66649f-1c6e-46ae-912b-4206278f569b END:VCARD
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