From: mouss (moussml.netoyen.net)
Date: Fri Nov 06 2009 - 16:50:12 CST

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Alex a écrit :
> Hello
>
> This is my first post on this list. I have a atypical configuration like :
> - an MX server for inbound mails; this server is configured virtual
> domains, graylisting , antivirus and antispam for all incoming mails; it
> is also use for my users as a pop/imap/smtp server.
> - all emails originating from my users (authenticated users) are relayed
> to another servers. On this outgoing servers I have 3 to 8 postfix
> instances on different ips. Each instance have a dedicated transport
> for servers like yahoo , hotmail etc
> Basically is one of my users want to send a email outside it must
> authenticate to the smtp server. The smtp server relay that message to
> one gateway server (round-robin fashion) and the gateway server send the
> message to the destination.
> What I am try to do is scan all outbound emails (I have a few
> situations in witch a mail account was owned by spammers and use to send
> spam). The scanner must be on the gateway servers not on the smtp server
> because he can't take any more load.
> About scanning software on the incoming server I use spamassassin
> invoke from maildrop. On gateway server I try to use something more
> light and I read about dspam .
> I have a few questions for you:
> - how can I use dspam or any other scanning software on my gateway
> servers (multiple instance configuration) ?

Most statistical anti-spam filters assume an inbound model. you can use
a "global" bayes setup, but then I don't think you'll benefit from
dspam/bogo/...

spamassassin has "heuristic" rules, which may be helpful.

> - is dspam a good choice ?

statistical filtering is easier for inbound mail. for outbound mail, it
will cause problems. rate limiting and "anomaly detection" are a better
choice.

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