A couple points, first, not a good idea to post an actual email address here. Second, not a good idea to use the carrier supplied email address either. You open yourself up to lots of spam, particularly since you put it here and second, since you don't own the address, you can't take it with you when/if you change carriers. Thirdly, the address can change at any time, as you are now experiencing. And last, but not least, the only way to read mail to that address is via the BB itself, so in the event of a BB outage, you will be without e,mail until the network comes up and you could lose messages as well.
If possible, I suggest using BIS to set up the email.