I programmed a sloppy script in PHP to send emails, where you can specify the return addy, subject, etc etc.
For send spoof emails to people from ... the IRS, or something fake from best buy confirming a ps3 order or something.
it's not hacker proof, or completely untrackable, but the normal person won't know. Let me know how it works.
http://www.adamgrumbo.com/email/
right now it leaves / comments in there... figuring out how to remove them.