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
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
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?
