The Get-Mailbox cmdlet does not return the correct server information in Microsoft Exchange Server 2010.
This issue can occur if the mailbox was moved to a different Database Availability Group (DAG).
To work around this issue, use the Get-MailboxStatistics cmdlet to obtain the correct server information.
In Exchange Server 2010, a mailbox object is associated with a database, and copies of the database are associated with a server. When a client or application tries to access the mailbox that is hosted on Exchange Server 2010, Active Manager refers the request to the server that hosts the active copy of the database.
Note In Microsoft Exchange Server 2007 and in earlier versions, a mailbox object was associated with a server.
For more information about mailbox attributes that are not updated when an Exchange Server 2010 mailbox is moved, see the following TechNet website: