UPDATE!!!
I went to the Apple Store yesterday, and now it all works!! The problem is simple....In the mail settings, where the outgoing server is "smtp.comcast.net", the username and password is blank. It is blank because from your computer, it does not need to authenticate but since this is a diff IP address, you MUST put in the username and password! It now works fine on WiFi AND EDGE, so check those settings. I saw that before but never tried it because I assumed the computer transferred the correct settings upon syncing. Anyways, good luck!