Users cannot use Outlook to access their mailbox after migration to Exchange 2010

Consider the following scenario:

• A user has a mailbox that is hosted on a server that is running Microsoft Exchange Server 2003.
• You run the Prepare-MoveRequest.ps1 script to prepare to the mailbox for a migration to Microsoft Exchange Server 2010.
• The user tries to access the mailbox that is hosted on Exchange Server 2010.

In this scenario, the user cannot access the Exchange Server 2010 mailbox by using Microsoft Outlook.

This issue can occur if duplicate legacyExchangeDN values exist in the source forest.

To resolve this issue, install Microsoft Exchange Server 2010 Service Pack 2 (SP2). For more information about Exchange Server 2010 SP2, visit the following Microsoft website:

The Prepare-MoveRequest.ps1 script locates a mail contact and converts the mail contact into a mail-enabled user. The Prepare-MoveRequest.ps1 script also runs the Update-Recipient cmdlet to populate the legacyExchangeDN value for the user. The legacyExchangeDN value is written back to the source forest as an X500 address.

The Update-Recipient cmdlet generates unique legacyExchangeDN values in the target forest. However, duplicate legacyExchangeDN values may be generated in the source forest. After you install Exchange Server 2010 SP2, a three-character random number is appended to the legacyExchangeDN value to help ensure that the value is unique.

For information about how to prepare mailboxes for a cross-forest move by using the Prepare-MoveRequest.ps1 script, visit the following Microsoft TechNet website:For more information about the Update-Recipient cmdlet, visit the following Microsoft TechNet website: