Was scrolling through the maillog just now, nothing out of the ordinary other 
than list traffic that I can tell.

So no, all inbound mail comes to the Barracuda, gets cleaned and sent to the 
Mailman server.  Each day about 600 inbound junk mails get blocked and around 
50 legit emails.  It is hosting just lists only, no other inbound or outbound 
mail.  Outbound does get sent directly out the Postfix and is not sent through 
any smart host.

Good question on the verifying recipients - not quite sure the exact answer - I 
think the mailman server is processing bounces because I'll see bounced emails 
in the log to "johnsm...@lists.mydomain.com does not exist".  So invalid 
recipients do seem to hit the Mailman server.  Maybe filtering recipients at 
the Barrcuda could help?

On the note of the traffic - today everything is fine.  Not sure why for 5 days 
it was consuming the pipe, but have not found any indication of an open relay 
or malicious intent.  We did throttle back the simulaneous connections, maybe 
that will help a bit.

My Postfix maillog shows a ton of these:

(lost connection with spool.santarosa.org[216.222.240.7] while sending end of 
data -- message may be sent more than once)   

and

(conversation with mail.laguna-hills.ca.us[68.203.215.26] timed out while 
sending end of data -- message may be sent more than once)  

 11,968 matches of (lost connection) and 9202 matches of (conversation with) in 
a log file covering 4 days (Nov 21 01:18 - Nov 24 9:07).

One thing that did change was the internal DNS servers on the network, I almost 
have to assume it has to do with that.....


-----Original Message-----
From: Andrew Hodgson [mailto:and...@hodgsonfamily.org] 
Sent: Wednesday, November 24, 2010 10:34 AM
To: Scott Race; mailman-users@python.org
Subject: RE: [Mailman-Users] Mailman server consuming entire Internet pipe 
(dual T1)

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. 


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