If this is not a performance issue due to:
CPU issues on the CAS or Mailbox Servers
Disk latencies on the Mailbox Server
Then consider the follwoing:-
1) Update 5.0.2 Maintenance Release 4 of Blackberry Enterprise Server...
Update Rollup 3 for Exchange Server 2010 Service Pack 1
http://support.microsoft.com/kb/2492690
Update Rollup 3 for Exchange 2007 SP3
http://support.microsoft.com/kb/2492691
This notification is to let you know we published a revised version of Exchange 2007 SP3 RU3 (v2 ) .
The Exchange Servicing team has fixed the reported issue with RU3 and is making available a new version of RU3 for our customers, which is version...