You do realize that those make up quite a large percentage of the email addresses around, right?
/solution
Send out one mass mailing with some crappy shit that makes people want to unsubscribe. Include an "unsubscribe" link. When they click it, the user's email is verified as real, and his IP is recorded.
Now you have a 100% active list sorted by region
(do not try this at home unless you are an annoying spammer)