Question : Moving to another Exchange 2007 Server, do I do anything on the BES for BB mail?

Hi, I am moving my users to a new Exchange 2007 Server (all functions except Edge).  I am also running BES Express.

Is there any configuration needed on the BES when I begin migrating mailboxes?

Answer : Moving to another Exchange 2007 Server, do I do anything on the BES for BB mail?

If you move a mailbox to a new server the MAPI session should pickup the change and you 'should' not have to do anything

If the BlackBerry smartphone user's mailbox has been moved to a different Microsoft Exchange Server, the BlackBerry Enterprise Server should recognize this change after a short period of time. If the BlackBerry Enterprise Server does not recognize the change, run the handheldcleanup.exe utility from the default mailbox location. For more information on the handheldcleanup.exe utility, see KB00140.
http://www.blackberry.com/btsc/search.do?cmd=displayKC&docType=kc&externalId=KB00140&sliceId=SAL_Public&dialogID=32561512&stateId=0%200%2032563545

In reality - I have sometimes had to delete and re-add the users.