detecting viruses in attachments?

["Paul L. Schumacher" <wnpauls @ linux . winona . msus . edu>]

I just had a list get hit with a virus in an attachment.  We catch them
quickly  - after - they are sent an can warn everybody.  A few on the list
get the virus.

Any suggestions on detecting viruses and bouncing them before they are
resent.  Or suggestions on detecting attachment and removing them before
they are sent will be appreciated.

thanks, 

Paul L. Schumacher
Winona State University
Computer Science Department