Then that would be BIS (BlackBerry Internet Service) vs. BES (BlackBerry Enterprise Service.) The latter is for corporate email.
I would tend to think the problem is on your device if you are unable to SEND BlackBerry email. Have you tried a battery pull yet? Pull the battery out for 30 seconds while the device is ON. Replace and try again after reboot completes.
A problem RECEIVING email may be indicative of a larger problem, but it's unusual for you to not be able to send email.