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While searching for an easy way to incorporate SpamAssassin in our organisation we were looking for a proxyserver/firewall kind of way.
On the \[http://www.spamassassin.org/doc.html Documentation\] page there are some good links that point in ways related to \[http://www.geekly.com/entries/archives/00000155.htm ProcMail\], \[http://advosys.ca/papers/postfix-filtering.html PostFix\] and Other solutions.unmigrated-wiki-markup Wiki Markup
If you are looking for something more basic that just does basic filtering (no user specific filtering!) you can consider \[http://www.rudedog.org/assassind/ assasind\].
Assasind can easyly be put inbetween your NAT and your propriety mail server, work 'on' your mail server or if you have a separate firewall running Linux you can place assassind there.
Assasind will listen at the appointed port (default:2025) for incoming SMTP traffic. Depending on the settings, mail will be scanned by SpamAssassin and/or Fprot for viruses. When done, assassind will forward it to the real mail server (default localhost:25)unmigrated-wiki-markup
From \[http://www.rudedog.org/assassind/assassind.man.html the manual\] :
assassind is a relaying SMTP proxy that filters spam using SpamAssassin. The proxy is designed to be robust in the face of exceptional errors, and will (hopefully) never lose a message. In addition to scanning for spam, assassind can optionally scan for viruses using F-Prot.
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