07-26-2013 03:40 PM
Hi and Welcome to the Community!
If this is for BES, then stop now and seek support from your BES admins.
But, if this is for BIS-based email, then with a strong carrier network signal (e.g., not merely WiFi), I suggest the following steps, in order, even if they seem redundant to what you have already tried (steps 1 and 2 each should result in a message coming to your BB...please wait for that before proceeding to the next step):
1) Register HRT
2) Delete and Resend Service Books (pre-BB10 devices only)
Hopefully that will get things going again for you! If not, then you should try deleting and re-adding your configurations for the affected email accounts. Otherwise, you should contact your mobile service provider for formal support.