Christopher Dargel's Exchange and Windows Blog

Today I’ll post my favourite way to move user and mailbox objects across forrests.

1. Prerequisite: Transitive AD trust, migration server running ADMT
2. Migrate the user object with ADMT
3. Mail enable migrated users with PowerShell
   

   Enable-MailUser -Identity user -ExternalEmailAddress user@domain.com

4. Collect both domains’ credentials
   

   $LocalCredentials = GetCredential
   $RemoteCredentials = Get-Credential

5. Prepare move with “prepare-moverequest.ps1” from Exchange servers’ scripts folder
   

   .\Prepare-MoveRequest.ps1 -Identity user -RemoteForestDomainController dc.olddomain.com -RemoteForestCredential $RemoteCredentials -LocalForestDomainController dc.domain.com
   -LocalForestCredential $LocalCredentials -TargetMailUserOU “OU=Users,DC=domain,DC=com” -UseLocalObject –LinkedMailUser

6. Move mailboxes
   

   New-MoveRequest -identity user -RemoteLegacy -TargetDatabase MAILBOXDATABASE -RemoteGlobalCatalog dc.olddomain.com -RemoteCredential $RemoteCredentials -TargetDeliveryDomain
   domain.com

There’s a GUI for cross-forrest-moves, too:

Cross Forrest Mailbox Move GUI

Refer to this TechNet Blog article for further details.

Cheers,

Chris