Article ID: 953611
When you move a mailbox from Exchange 2000 to Exchange 2007 in a mixed environment, the move-mailbox operation is not successful if the mailbox owner has the items that were read in more than 819 public folders. When this issue occurs, the error code "-1056749164" is returned.
To resolve this problem, install the most current security update for Exchange 2000 server. To install the most current updates, visit the following Web site:
http://update.microsoft.comNote This problem was first resolved in security update 959897 (MS09-003). For more information about this update, click the following article number to view the article in the Microsoft Knowledge Base:
(http://support.microsoft.com/kb/959897/ )MS09-003: Description of the security update for Exchange 2000 Server S959897 and Exchange Server 2003 S
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.