I am a delegate but can't access the shared mailbox or folders of the principal
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Applies to: Office for Mac 2011
Topic Last Modified: 2012-06-07
Cause: You cannot access the shared mailbox or folders of a user whose mailbox is on Exchange 2007 server when you are connected to Exchange 2010 or vice versa.
Solution: Move the principal's and each delegate's mailbox to the same Exchange Server version.
Exchange Web Services, the protocol used by Outlook 2011 and Entourage 2008 Web Services, only allows delegate access if both the principal's mailbox and the delegate's mailbox are on a computer that is running Exchange Server 2010 or Exchange Server 2007.
If you try to access a shared mailbox for a user on another Exchange Server 2007 when your mailbox is on Exchange Server 2010 or vice versa, you will see the following error: "The account accessing the resource must be on the same Mailbox Server version as the delegate account being accessed. "