A user cannot access a Microsoft Exchange Server 2010 mailbox intermittently after the mailbox is moved. However, the mailbox can be accessed after some time, within two hours.
When the moving operation is complete, the homeMDB attribute, which is an Active Directory attribute, is updated. However, in a multiple domain controller (DC) environment, it takes some time for the homeMDB attribute to replicate to all domain controllers in the site. If a user tries to log on to the mailbox before the target domain controller has updated the homeMDB attribute, the connection is unsuccessful. In addition, the related attributes is cached by Exchange Information Store for up to two hours. Therefore, the mailbox cannot be accessed during this period.
To resolve this problem, install the following update rollup:
982639 Description of Update Rollup 4 for Exchange Server 2010
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.