So today at work I was playing with procmail. I'm on the Netsaint mailing list and I'm tired of getting the email. I might need it later, so rather than unsubscribe I setup the following procmail rule.

:0:
* ^Subject:.*[netsaint]
mail/netsaint

Nothing wrong with that... or so I thought until I stopped getting email. Then I realized that you have to escape those [ ]... So basically any email that came in with one of the letters: n,e,t,s,a,i,n in the subject was getting deleted. That's damn near everything :) Oooops