Removing Ghost-Mailboxes from Exchange 2010/2013
In Exchange you can encounter issues when you move mailbox between databases. And after this issues you can have, for example, 2 (or several) mailboxes in your databases which belongs to a single user. And of course, only one mailbox from them linked to Active Directory user account.
And one more thing - mailboxes that are not used, NOT marked as Disconnected or SoftDeleted.
These mailbox are known as ghost-mailboxes.
They are located in databases, waste hard drive space and they are not used. So you want to delete them. How?
First of all, you must get the mailbox GUID in database:
Get-MailboxDatabase MDB-001 | Get-MailboxStatistics | select displayname,lastlogontime, itemcount, mailboxguid | Out-GridView
Copy GUID. Next:
Remove-Mailbox -Database MDB-001 -StoreMailboxIdentity 67879cee-6531-4586-85e4-76895edcedb4
Eith this method you can also delete others unneeded mailboxes from database, for example SoftDeleted and Disconnected (if you dont want to wait 30 days).