How to delete orphaned mailboxes

I have no clue how this could happen:

Get-MailboxStatistics -Server returns 2 exactly equal entries Office [Foo Software] [It shows the used format]. One mailbox has 411 ItemCount, the other has 7.

In the Exchange Management Console there is no user associated to these mailboxes and Get-Mailbox does NOT return these 2 entries. Get-User shows users which have another mailboxes. It looks to me as Exchange has here some inconsistency.

Also, in Exchange Console under Recipient configuration I see a disconnected mailbox with the name Office [Foo Software] - Trying to connect it fails because no proper user is found.

How can I delete this 2 equal and orphaned mailboxes? It's true, I had users with this name but I deleted them in the Exchange Management Console.

Environment:

• Exchange Server 2010
• SBS 2011 Standard

Update:

In the meantime I could at least delete the one mailbox with 411 ItemCount. Also, the above mentioned disconnected mailbox disappeared from the Exchange Management Console.

Get-MailboxDatabase | Get-MailboxStatistics | Where{ $_.DisplayName -eq "Office [Foo Software]" } |fl DisplayName, Database, Identity, DisconnectReason returns now this:

DisplayName      : Office [Foo Software]
Database         : Mailbox Database
Identity         : f3ed13de-ae8a-4c0a-9d4d-b641d35e0335
DisconnectReason : 

When I try to disable this mailbox with Disable-Mailbox -Identity "f3ed13de-ae8a-4c0a-9d4d-b641d35e0335" then I get the error that the mailbox doesn't exist.

I have to disable it first because when I try to remove the mailbox I am asked for the MailboxState but it cannot be empty.

So, now the question is, how can I delete the mailbox using its uuid?

With this steps I could delete the remaining Office [Foo Software] mailbox:

1. Run in the Exchange Powershell Get-MailboxStatistics -Server '<ServerName>' | WHERE {$_.ObjectClass -eq "Mailbox"} | FL DisplayName,LastLoggedOnUserAccount,MailboxGuid.
2. LastLoggedOnUserAccount has the name of the user which was previously assigned to this mailbox.
3. Create this user again BUT ONLY in the AD - NOT as an Exchange user.
4. Connect manually the new AD user with Connect-Mailbox -Database "Mailbox Database" -Identity "Office [Foo Software]" -User <LastLoggedOnUserAccount> to the mailbox.
5. Delete the user in the Exchange Management Console. Now its mailbox is marked as Disabled.
6. Remove the mailbox with Remove-Mailbox -Database "Mailbox Database" -StoreMailboxIdentity "f3ed13de-ae8a-4c0a-9d4d-b641d35e0335" where StoreMailboxIdentity is the value returned in 1) as MailboxGuid

I don't claim this is the simplest way, but it worked for me. Now both mailboxes with the same DisplayName have been successfully removed from the Exchange.