Exchange 2003 To Exchange 2010 Swing Migration Problem
This problem occurs because the federated built-in e-mail account that links to the computer account no longer exists. Or
the federated built-in e-mail account in the Active Directory directory service is corrupted
Fix
Remove the FederatedEmail.4c1f4d8b-8179-4148-93bf-00a95fa1e042 e-mail account by using the ADSIEDIT tool. To do this, follow these steps
Click Start click Run type adsiedit.msc, and then click OK
Locate the Default Naming Context node and then locate to the CN=Users container
Locate and then right-click the CN=FederatedEmail.4c1f4d8b-8179-4148-93bf-00a95fa1e042 container. Then clickDelete
http://support.microsoft.com/kb/978776