A simple plan
Can we all agree that no one is legitimately going to e-mail a ".pif" file as an attachment to anyone? Every mail server/client in the world should be deleting these things automatically, upon arrival.
While we're at it, lets add ".exe" files too. The only legitimate EXE files that get mailed around are those stupid little games people are always forwarding to one another. They're probably carrying spyware too.
And ".scr" files.
And anything else that is a binary executable.
Oh, let's not forget those Word and Excel documents that carry