[Exim] filtering viruses

I know this has been discussed on this list before. I know you can use
Exim (and other MTA's really) to filter out emails with virus
attachments and so forth.

But, wanting something more portable, and a little less drastic for some
users, what is the best way to do this with procmail?

I know this is slightly O.T. so please respond to me directly and
pointers to web documentation is fine.

Thanks.

--
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    __   _                                           Carl B. Constantine
   / /  (_)__  __ ____  __                          duckwing@???
  / /__/ / _ \/ // /\ \/ /  (2.4.18)              http://www.duckwing.ca
 /____/_/_//_/\_ _/ /_/\_\  Debian 3.0
                                            PGP key available on request
________________________________________________________________________

"Microsoft is not the Borg. The Borg have better tech support."