[afnog] spam filter for smtp

[Mark Tinka]

On Thursday 10 June 2010 11:35:45 pm Noah Sematimba wrote:

> We used to have a commercial solution from CA which
>  became a major enough annoyance with e-mail delivery
>  delays that we were able to finally convince management
>  to "see the light" and let us try and open source
>  solution. So we now use mailscanner with postfix on
>  OpenSuSE. http://www.mailscanner.info and it works
>  beautifully.

My experience was the reverse, when I used to Sysadmin - or 
maybe I was lazy :-).

Sophos' PureMessage for UNIX worked like a charm, doing a 
respectable 98% job of capturing spam with no false 
positives.

It's based on Postfix (with a Postgres SQL backend) and runs 
well on any Linux system (we ran it on openSuSE):

http://www.sophos.com/products/enterprise/email/security-
and-control/unix/

It's been several years since I ran a mail system of this 
magnitude (several thousand users, then) so a lot could have 
changed, but PM supports clustering and separation of 
database and mail message handling. This helped us scale the 
platform.

One thing they did need to fix was quarantine management. 
That was a pain for users to setup and manage since each 
session required its own setup process. User customization 
was also painful. But again, it's been a while - this could 
have been fixed.

It also provides support for virus checking (which can be 
turned off, if you like). Spam heuristics and virus 
signatures are updated automatically.

One important thing to note is that PM does filtering as e-
mail comes into the network, not at the user level (as mail 
is dropped into the mail box), although I'm guessing there's 
some way this can be achieved with PM. You can choose to 
scan e-mail uni- or bi-directionally. This may influence 
whether you think it's right for your situation.

You can try it for free for 30 days.

Hope this helps.

Cheers,

Mark.
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