If you do use procmail, you can use virus.email to send a message as a bounce back. :)
Right. That way you can send bogus bounce notices to people who didn't send you attachments in the first place, thus doubling the amount of traffic generated by a virus outbreak without actually notifying the people whose computers *are* infected.
Unfortunately, that's all you can really do when you're blocking solely based on file extensions: you can't separate clueless senders from viruses, so you can't just silently discard things without risking false positives.
Kelson Vibber
SpeedGate Communications <www.speed.net>