http://exchangeserverpro.com/reconnect-disconnected-mailbox-exchange-server-2010/

--> opvragen disconnected mailboxen
[PS] Get-MailboxStatistics -Database "Mailbox Database 1780519836" | Where-Object {$_.DisconnectDate -Notlike $NULL} | FL DisplayName, DisconnectDate, MailboxGuid

To reconnect Alan Reid’s mailbox to his existing Active Directory account we would run this command.

[PS] C:\>Connect-Mailbox -Identity "Alan Reid" -Database MB-HO-01 -User Alan.Reid

However, if the user already has a new mailbox they are using and you wish to restore the disconnected mailbox into that new mailbox then you would use the next method shown here.

How to Restore a Deleted Mailbox to a User’s Mailbox

A soft deleted mailbox needs a different method used. To restore the deleted Aisha Bhari mailbox to the current mailbox for that user we would run this command.

[PS] C:\>New-MailboxRestoreRequest -SourceDatabase MB-BR-01 -SourceStoreMailbox "Aisha Bhari" -TargetMailbox "Aisha Bhari"

Name                                           TargetMailbox                                  Status
----                                           -------------                                  ------
MailboxRestore                                 exchangeserverpro.net/Company/Users/Branch ... Queued

The request goes into a queue for processing. You can monitor the progress of the request with this command.

[PS] C:\>Get-MailboxRestoreRequest

Name                                           TargetMailbox                                  Status
----                                           -------------                                  ------
MailboxRestore                                 exchangeserverpro.net/Company/Users/Branch ... Completed