I'm performing a cross-forest migration using Prepare-MoveRequest.ps1, Identity Lifecycle Manager and Active Directory Migration Tool.
After a windows 7 PC was migrated to the new forest the user account and his mailbox, Outlook 2010 continued to reference the old Exchange 2003 servers which were failing to refer the user to the new Exchange 2010 servers in the new forest.
I created an Outlook PRF file with the following configuration:
;ServiceX=Microsoft Outlook Client
ServiceEGS1=Exchange Global Section
Service1=Microsoft Exchange Server
I attempted to import the PRF into Outlook 2010 using the following command:
outlook.exe /importprf path:C:\outlook.prf
During the import the following error was experienced:
An unknown error occurred, error code: 0x80070057
This turns out to be a bug with Outlook 2010 importing PRF files. I found this on knowledge base 2028193.
After installing the following hotfix my problem was resolved: