Question : Creating new mailbox error: ExchangeGuid is mandatory on UserMailbox

When we try to create a new mailbox on our Exchange 2007 servers we receive the error: ExchangeGuid is mandatory on UserMailbox. No events are loged in the Event viewer. This error happens if we create the user first in ADUC and try to create the mailbox or if the user and mailbox are created in the EMC.

Answer : Creating new mailbox error: ExchangeGuid is mandatory on UserMailbox

Can you run the Update-emailaddresspolicy command from the EMS and see if that updates the mailboxes? If not are you seeing any error messages?

Update-EmailAddressPolicy
http://technet.microsoft.com/en-us/library/aa996869(EXCHG.80).aspx

http://msexchangeteam.com/archive/2006/10/02/429053.aspx