No, unfortunately not... since the system doesn't know the IP address of the person checking the mail (the mail is already sent at that point), and there's no way to get an existing mail to report back the IP of the reader anyway.
Yea, I wasn't sure if you was collecting the user data through the forums, such as their location. I think Adknowledge does something similar like this. They collect user e-mails through high traffic powered sites. They also collect the users location as their surfing through these sites. Therefore your able to target by location.
From a technical standpoint, it could be possible to do it based on their registration IP or something, but that's going to be less than ideal since someone could have registered 6 years ago, and might not necessarily be in the same country any longer.
True, but you could always stay up to date with them through the forum. Monitor their location from time to time. Which of course I'm sure your aware of that. Shawn, by the way you probably remember who I am or you might not. I didn't realize you live in San Diego. I just moved out to LA near Venice. California is much better