User %1 (%2) failed to log on because their mailbox is in the process of being moved.

This event indicates that the mailbox for the user specified in the event description is being moved from one server that is running Microsoft® Exchange Server to another Exchange server.

No user action is required. Users will be able to log on to their mailboxes as soon as the move mailbox process is complete.

If you are not already doing so, consider running the tools that Microsoft Exchange offers to help administrators analyze and troubleshoot their Exchange environment. These tools can help you make sure that your configuration is in line with Microsoft best practices. They can also help you identify and resolve performance issues, improve mail flow, and better manage disaster recovery scenarios. Go to the Toolbox node of the Exchange Management Console to run these tools now. For more information about these tools, see Toolbox in the Exchange Server 2007 Help.