[Mailman-Users] emails from mailman rejected with error "reject=550 Relaying denied. IP name possibly forged"

[Stephen J. Turnbull]

Abdullah AL-Maskari writes:

 > I will look at the spam filter configurations and my DNS but I dont see 
 > how any of those systems could be broken if the original mailman server 
 > is working fine.

It's not a question of whether something is broken; something is.  The
fact that your own logs record that your mailhost "may be forged"
proves that.  The questions are what it is, and whether this breakage
is causing you problems.[1]  If you have another Mailman host that works,
you can check for differences in their configurations (including the
list memberships!), as well as any aspects of the mailhost
configuration that might treat them differently.  But I still think it
would be a good idea to configure your mailhost so that in the DNS it
looks like a responsible citizen rather than a 'bot sending spam.

It occurs to me that the DNS problem may be that your HELO hostname
(in the SMTP transaction) doesn't match the reverse lookup for the IP
observed in the TCP connection.  That should be easy to fix in the
Sendmail configuration.

As for spam filters, it's probably not your spam filters that are
rejecting your mail, it's filters on the recipient hosts.  It's hard
to tell from the log, though.


Footnotes: 
[1]  You'll have to figure those out for yourself because you've
redacted all useful information about your network.  That's entirely
up to you, of course, and it's more secure.  But if you insist on
security, you're going to have to take our wild guesses seriously.