Re: [exim] exim can't handle 521 response from remote MX

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Autor: Heiko Schlittermann
Data:  
Para: exim-users
Asunto: Re: [exim] exim can't handle 521 response from remote MX
Hi,

krzf83--- via Exim-users <exim-users@???> (Fr 27 Aug 2021 13:10:01 CEST):
> Large email provider in my country uses 521 response at their MX for
> some kind of delaying. They don't care that its against rfc1846
>
> rfc1846 says:" A host which sends a 521 greeting message MUST NOT be
> listed as an MX record for any domain"
>
> # nc mx.poczta.onet.pl 25
> 220-mx.poczta.onet.pl ESMTP
> 521 5.7.1 Service unavailable; client [144.76.50.172] blocked using
> postscreenbl.opbl.onet.pl.local


From m PoV, they clearly state that they do not want connections from
your IP. Not now, and not later.

> Exim can't handle this and does not even log anything in that
> situation. Exim does not retry delivery and after 72 hours fails and
> returns message with


I believe, Exim logs that.

>     all hosts for 'onet.pl' have been failing for a long time (and
> retry time not reached)

>
> How can I make exim to log those delivery attempts that end with 521
> response? How can I make exim retry deliveries that ended with 521
> response?


5xx means: permanent failure. Period. If their intention is something
else, it is up to them.

Maybe some of them is reading on the mailops list. Try contacting them
there.

    Best regards from Dresden/Germany
    Viele Grüße aus Dresden
    Heiko Schlittermann
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