It hasn't happened to me (yet). What I do is draft up an e-mail saying everything I really want to say. But, I leave the TO address blank so that I don't accidently send it. Then I save it and read it back later ~ preferably the next day. I edit it and send it if I still feel strongly about it. But, 95% of the time, I end up deleting it and never sending it because life is too short. Most things are not that important and blow over relatively quickly. What is it they say?

Rule 1: Don't sweat the small stuff
Rule 2: Almost everything is small stuff