e-mail spoofing

Their are many ways to spoof email addys, you'll find that (without having to code a tool of anything) if you look hard enough you can actually find places online that will do it for you by default though... they probably wont know this though, http://readnotify.com/ is a good example and their are many others.

P.S on the whole tracking an IP from an email addy thing, using a sniffer has to be one of the best methods.