This is more difficult to do but it would be cool if it was a dynamic map showing both incoming and outgoing email. You'd need to lookup the MX records for the recipients and make best guesses for where the email is going. Then you can have a map run over time and show the emails coming and going, and have areas with a mre traffic that others get brighter, burst, something along those lines. I have a piece of software in mind but can't remember the name of it at the moment, I'll check around and see if I can find it.