The most logical email address would be first.last@NORAD.af.mil (and in Teal'c's case, just first) as it would jibe with their theoretical cover story. The shift to af.mil has begun only in recent years, but in the time period you are referring to email addresses would have been tied to the actual base.

btw, Peterson AFB is about 30 minutes across town from the approximate location of Cheyenne Mountain Air Station and the Air Force Academy is about 30 minutes north. Fort Carson, on the other hand, is about 10 minutes away. I always wondered why medical emergencies (like off world refugees) were not routed to the nearby Army base instead of the Academy :)