Outbound and Inbound mail on same server

Randy Herban RHerban at GRAMTEL.NET
Tue Feb 4 18:02:55 GMT 2003

Not that I have anything against Exim, I have never touched it.  But from
what I have seen with other MTAs (postfix and dmail mainly) is they have
very poor queue management.
Sometimes the only notification of a problem is items in the queue and
reasons why they can't be sent.  Neither of the two programs I mentioned
allow you to do some of the things you can do with sendmail and it's queues.

Quick shell script to delete all mailq items from a certain domain (say,
used to spam messages).
Easy way to count/sort the items in mailq to determine which domains have
the most in queue.
Process all mail in queue destined/from a certain domain.

Items like this tend to drive me back to 'old faithful'.  Ugly as sendmail
is, it has ALWAYS proven itself time and time again to help get the job


-----Original Message-----
From: David Sullivan [mailto:David.Sullivan at BARNET.AC.UK]
Sent: Tuesday, February 04, 2003 12:46 PM
Subject: Re: Outbound and Inbound mail on same server

On 4 Feb 2003 at 12:12, Randy Herban wrote:

> Background:
> We support mail accounts for several tens of thousand customers.  The
> majority of the mail we deal with is spam coming into our accounts
> using dictionary attacks or the like. With this in mind, the majority
> of the mail in the Outgoing queue at any time are MAILER-DAEMON
> messages with bounce-backs of user unknowns tryin to send mail to a
> host that doesn't accept mail.
If you're running a mail server that acts as a "gateway" mail server like
this it might be worth looking at exim, I'm not intending to start an MTA
war with such a comment but this is very easy to do with exim 4 acls which
can reject a message at the SMTP stage if recipient callout checks determine
that the address isn't valid. I don't believe that sendmail can do similar
but I couldn't say for sure.

Relevant section of the manual:


The section mentioning resource usage is probably less of a problem now
since caching for these callouts was included in 4.11 but the documentation
has not yet been updated.

If you're then not accepting these messages to users that don't exist and
not scanning them or trying to send bounce messages this might resolve some
loading issues.



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