What times does it not receive email? I'd say it was the automatic setting to not receive email between certain times has been changed, though you said you'd changed nothing. Send some test messages at different times to see when the problem starts and stops. If you find the messages stop from, say, 10pm to 7am, I'd say there are settings somewhere telling your bb to cut messages at that time - I know mine does!
Check options/ auto on/off is disabled. Anyone think of another area that controls messages? You got any 3rd part software on there that could be affecting messages?
Posted from my CrackBerry at wapforums.crackberry.com
I just checked the auto on/off and it was set to disabled. I turned them to enabled, saved, then turned them back to disable. We will see if that works or not.
Reconcile suggests BES? Are you sure there's no overnight maintenance happening around the server? Change of server settings - maybe administrator applied as a group option?