This post is not about taking a mailbox that has been inactive. Rather, this post is about taking an active mailbox that is already attached to an AD user and attach it to a different one.
Situation: Cross-forest migrations have a lot of moving parts. It requires two AD forests with accounts or trusts established, each with its own Exchange organization and proper mail flow with both a shared namespace and unique namespaces for routing mail and co-existing. To make it work, you need an AD account in the target forest that gets the ExchangeGUID of the mailbox stamped onto it as a MailUser. Sometimes there is a lack of control or an existing situation. In this case, AD replication was significantly impaired and after running the Prepare-MoveRequest.ps1 script, the AD user did not respond back that it had the ExchangeGUID attached, so it created a new account. The migration was successful, but to the wrong AD user. It was necessary to attach it to the proper AD User.
- Save the mailbox to a variable in the Exchange Management Shell
- Determine if it is desirable to delete the AD user, or not
- Take the desired action, then connect the mailbox to the desired target AD user
$Mailbox = Get-Mailbox <Identity> $Mailbox | Remove-Mailbox # Deletes the AD user #$Mailbox | Disable-Mailbox # Disabled the AD user Connect-Mailbox $Mailbox.ExchangeGuid ` -Database $Mailbox.Database ` -User "<Identity of target mailbox>"