Recently one of our client's Blackberry smartphones stopped receiving emails from their Blackberry Enterprise Server. Usually resetting the device by pulling out the battery resolves issues such as this. Ironically, she could send emails from the device just fine, plus the 10 other devices connected to their BES and network infrastructure were working normally.
RIM has several resolutions to this problem, which corrected the issue. I first verified email redirection was enabled, and the correct inbox folders were checked. Next I checked to make sure no email filters were enabled. Finally, the resolution was regenerating the encryption key on the device.
1. Click Options > Security > Security Status Information
2. Scroll to the Services section.
3. Highlight the Desktop [SXXXXXXX] line.
4. Press the Menu key and click Regenerate Encryption Key.
After regenerating the key, all new emails were received to the device.