On Thu, 2004-06-03 at 23:24, Dimitrios wrote: > On 03 Jun 2004 21:21:41 -0700 "Florin Andrei" <[EMAIL PROTECTED]> wrote: > > > I use Postfix + Amavisd-ng + SpamAssassin + ClamAV, everything works > > quite well. I'm thinking to add Razor. > > I always wondered whats the use of amavis, could you please explain > what is its use and why you need it? > Because i'm using a similar setup with SA and Clam, so i dont see where > amavis helps (SA cleans spam and Clam cleans viruses, whats left?).
Amavisd-ng, mailscanner and similar programs are essentially small mail relays that can run email through a variety of filter programs: anti-spam, anti-virus, sanitizers, etc. Of course you could interface all those programs directly with an MTA, but it's much easier with amavisd-ng/mailscanner: you just configure your MTA to route the mail through one of those apps, then you can add/remove filtering applications in amavisd-ng/mailscanner without ever touching the MTA itself, and indeed without disturbing the main email path too much. Wanna add ClamAV? Fine, just flip a switch in amavisd-ng. Wanna remove SpamAssassin? Flip another switch. Also, it's trivial to define global behaviour: run the email through several virus scanners, then trigger an action based on the overall results (drop the message, or send a warning to the recipient, or bounce a complaint to the sender, etc.). Also this method usually offers better performance than using a bunch of scripts to glue everything together (less hard-drive fracas). Another advantage is that it's really easy to run the MTA and the filtering apps on separate machines. Just take a look - all i can tell you is that my jaw dropped the first time i saw one of these apps, a couple years ago or so. I knew i had to use something like that. ;-) The only situation where it's not clear whether you have to use these things is when you only use one email filter: only spamassassin, or only an antivirus. But as soon as you want to run two or more (usually spamassassin + an antivir), it totally makes sense to use a better "glue" for all those filters. -- Florin Andrei http://florin.myip.org/
