Re: reject=553 5.3.0 127.0.0.2 due to unreachable DNS resolver

On 2/1/25 08:54, Marco Moock wrote:

Hello!

Hi

I had a situation where my DNS resolver was unreachable for my machine.

I would expect your logs to indicate /temporary/ failures in the case when a normally reachable / usable DNS server was unreachable / unusable.

Jan 31 23:37:37 pi-dach sm-mta[1034127]: ruleset=check_relay,
arg1=[157.230.63.40], arg2=157.230.63.40, relay=[157.230.63.40],
reject=553 5.3.0 127.0.0.2

The "553 5.3.0" indicates a permanent error, not a temporary error that I'd expect.

The remote machine gave
 <uk-legal-moderated@moderators.isc.org>: host pi-dach.dorfdsl.de[82.139.252.17]
     said: 553 5.3.0 127.0.0.2 (in reply to MAIL FROM command)

That sounds like your system was trying to send an email and the remote system refused to accept it.

If that is related to a non-resolvable domain (DNS timeout), what is the
reason for this strange error message?
 The dnsbl features give back different messages.

Please clarify:
  - which system the logs are from
  - which system was the sending server
  - which system was the receiving server / generated the "553 5.3.0" rejection
--
Grant. . . .