After I moved Blackberry-enabled mailboxes over from Exchange 2003 to Exchange 2007, there were no major problems as far as Blackberry was concerned – except that calendar items created on the blackberry devices did not get synchronized with Exchange/Outlook.
The primary reason for the problem is that Blackberry uses public folders to sync calendar items – and Exchange Server 2007 by default has no public folders!
To workaround the problem:
1 – Create a Public Folder database on the Exchange Server that has the mailbox server role installed.
2 – Link the Exchange Server 2007 mailbox database to the Public folder database you just created. To do this, open the properties of the mailbox database containing the blackberry user mailboxes and select the new public folder store in the Client Settings tab.