These are some BB\RIM existing issues that were caused by SP2 RU4. Below are KB articles written with details around the issues and resolutions\workarounds.

 

Exchange 2010 SP2 RU4 Blackberry\RIM Issues

KB:2797529
Email message delivery is delayed on a Blackberry mobile device after you install Update Rollup 4 for Exchange Server 2010 SP2

KB:2787500
Declined meeting request is added back to your calendar after a delegate opens the request by using Outlook 2010

KB:2779387
Duplicated email messages are displayed in the Sent Items folder in a EWS-based application that accesses an Exchange Server 2010 Mailbox server

KB:2800080
ErrorServerBusy response code when you synchronize an EWS-based application to a mailbox in an Exchange Server 2010 environment