When moving mailboxes from Exchange Online to Exchange 2016 on-premises in a hybrid environment, the move fails with an error “Cannot find a recipient that has mailbox GUID ‘ ‘
The error is listed here for Search Engine purposes:
Error: MigrationPermanentException: Cannot find a recipient that has mailbox GUID ’add02766-9698-48e6-9234-91c3077137bc’. –> Cannot find a recipient that has mailbox GUID add02766-9698-48e6-9234-91c3077137bc ’.
When checking the user account with ADSI Edit in the on-premises Active Directory it is obvious that this property is empty:
When checking the Mailbox in Exchange Online (using Remote PowerShell) the Exchange GUID is visible:
It took me some time to figure out why this property was empty. Normally when moving mailboxes from Exchange on-premises to Exchange Online the Mailbox GUID is retained. Keeping the Mailbox GUID makes sure you don’t have to download the .OST file again after moving to Exchange Online.
What happened here is that the user was created in Active Directory on-premises, and a Mailbox was directly created in Exchange Online using the Enable-RemoteMailbox command. In this scenario, there never was a Mailbox on-premises and thus never a Mailbox GUID.
The solution is to copy and paste the Mailbox Guid as found in the previous command into the Remote Mailbox object on-premises using the Set-RemoteMailbox command:
When setting the Mailbox Guid the mailbox can be moved from Exchange Online to Exchange on-premises.
Ps. Don’t forget to repeat this for an archive mailbox (if one exists)