I watched this video by Scott Hanselman yesterday. It makes a few really good points, one of which is:
Never write an eMail more than five sentences long. If you need to, write a blog post/webpage/wiki/etc and send them a link.
It’s such a good idea, and one I’m going to start using at work. I did used to do this, but then got into bad habits. I’m going back to try this again.