e mail source

Clarifications

Just highlight your email and then go to "view > message source", this will give you a few details of your message and even the ip address if you are lucky. :)

This will give you the location from where it came from. Though if it is spam mail it could have come from anywhere, these spam emails get bounced around a few locations before they arrive at your inbox.

Although it is getting very long in the tooth, I still like Sam Spade for parsing header information. Note, that spammers have become a little more devious when it comes to hiding the originating IP.
http://preview.samspade.org/ssw/download.html