Originally Posted by scorp508
Exchange doesn't talk to BES. Exchange has no idea BES is poking it all the time like a hot poker. BES scans the user mailboxes for changes and then performs the necessary actions to get them to the handhelds.
Sorry, but this is not true.
In Domino and Groupwise environments, BES scans the mailboxes on a schedule for changes... but this is not the case for Exchange.
Exchange uses MAPI and sends a UDP Notify packet to BES to alert it that there is a new message to be delivered.
If there is heavy network traffic, or some other reason to prevent the UDP Notify packet from reaching BES, only then will BES issue a mailbox rescan to have a look around.