[Mailman-Users] Mailman server consuming entire Internet pipe (dual T1)

[Andrew Hodgson]

Scott Race wrote:

[...]

>I've done some basic testing for open relays, so far I have not found anything indicating it's an open relay. Packet sniffing shows connections >from a number of IP addresses to the Mailman server.  Outside test shows the hostname is not an open relay, and I can't telnet on port 25 with >standard HELO command.  All internal mail comes to a Barrucuda spam filter unit.

>/usr/local/mailman/logs/post shows 19 posts today to the various lists.

The Postfix logs would be of more benefit I think here, as well as the mail queue.
 
You say you route mails through a Barracuda host, do you allow traffic directly into this machine on port 25 externally?  Is this machine hosting lists only, and if so, how is the Barracuda/Postfix server verifying recipients as early as possible (in case the domain is receiving large amounts of bounced mail and is rejecting with a full NDR and not a bounce at SMTP stage?  Does outbound mail get delivered direct from Postfix or are you smarthosting to the Barracuda?

Thanks.
Andrew.