Couple of other things if the carrier say everything looks good is to look to see if the Send Service, via Message Services under Advanced Options is set to your email account. Also you said this BB was originally setup on BIS. I would try (first backup device if you need items off of it) would be to wipe the handheld. If you have a newer device, look under Options > Security Options > General Settings, then click on the "menu" button of the BB, if you have an older device would be under Options > Security Options, then push in trackwheel.