Kadlecsik J?zsef:
> Hello,
>
> One of our users reported a rejected email with the error code and message
>
> Remote-MTA: dns; artemis.gat.com
> Diagnostic-Code: smtp; 550 Sender IP reverse lookup rejected
>
> We handle several domains with different outgoing smtp settings at
> multiple mail gateways:
>
> # /etc/postfix/master.cf
> wignersmtp unix - - y - - smtp
> -o smtp_bind_address=148.6.0.56
> -o smtp_bind_address6=2001:738:5001::56
> -o smtp_helo_name=smtp.wigner.mta.hu
> -o syslog_name=postfix-wigner-smtp
>
> # /etc/postfix/main.cf
> default_transport = kfkismtp
> sender_dependent_default_transport_maps =
> hash:/etc/postfix/sender_transport
>
> # /etc/postfix/sender_transport
> @wigner.mta.hu wignersmtp:
> ...
>
> The sender address was from the @wigner.mta.hu domain and the IPv4/IPv6
> addresses resolve to smtp.wigner.mta.hu. The HELO name is also explicitly
> set to this name. Using debug_peer_list I could verify that the wignersmtp
> transport setting is used for @wigner.mta.hu senders indeed.
>
> So, what kind of incorrect setting can the "Sender IP reverse lookup
> rejected" error message be mean?
It could be the same problem as GMAIL, where they would do a hard
reject after a temporary error during reverse DNS lookup.
At the time (years ago) I just turned on "-o soft_bounce=yes" for
those deliveries, so that the email would be delivered later.
Of course, soft_bounce is not ideal; nowadays I would use
smtp_delivery_status_filter to change the 5.*.* into 4.*.* for that
specific server response.
If the result of this is that mail stays in the queue, then
further investigation will be needed.
Wietse
