When you try to move mailboxes from a Microsoft Exchange Server 2007 server to a Microsoft Exchange Server 2010 server, certain mailboxes cannot be moved. Additionally, the following event is logged on the Exchange Server 2010 server:
This problem occurs when the mailboxes have been previously migrated by using third-party tools and the ptagCn property has been missed.
To resolve this problem, install the following update rollup:
2407025 Description of Update Rollup 2 for Exchange Server 2007 Service Pack 3
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
For more information about the ptagCn property, visit the following Microsoft website: