Move Mailbox Operations and the Mailbox Tombstone Table
Topic Last Modified: 2005-10-12
Microsoft® Exchange Server 2003 and Exchange 2000 Server use the Active Directory® directory service to store configuration and user information. Typically, most of this information is stored on a server separate from the server that is running Exchange, and the server that is running Exchange may use any of several Active Directory servers to read and write configuration changes.
Therefore, during a Move Mailbox operation, it is possible that source and destination servers that are running Exchange will read from or write to multiple Active Directory servers, and that it will take some time for Active Directory servers to fully synchronize with each other. This possibility can lead to situations in which mail delivery occurs to the source server instead of to the destination server during or after a mailbox move.
To handle this problem, the source Exchange database lists a moved mailbox on its mailbox tombstone table. This table is independent of any Active Directory information. If a message is delivered to the source server after a mailbox has been moved, the source server recognizes that, regardless of the information stored in Active Directory, the message should not be delivered here and reroutes the message. The error ecMailboxInTransit is returned when a delivery attempt is made, and the server then tries to reroute the message instead of delivering it locally.
If you use the Move Mailbox task to move a mailbox back to a server on which it was previously homed, the Move Mailbox task will clear the mailbox tombstone entry so that the move can succeed.
When a database is moved to a different server, the Mailbox Cleanup Agent will mark all mailboxes in the database as Disconnected. In addition, for the system attendant mailbox only, the Mailbox Cleanup Agent makes an entry in the mailbox tombstone table. This prevents a system attendant mailbox from one server from being activated on a different server.
However, this safeguard means that the database cannot be used again on the previous server to host the system attendant mailbox. This situation exists because there is no provision for removing the system attendant mailbox from the tombstone list. Move Mailbox does not apply to system attendant mailboxes. Because the mailbox tombstone table is not replicated or known in Active Directory, but is limited to a specific physical database, you can re-enable the system attendant mailbox by putting in place a physical database that has never had a tombstone entry for that system attendant mailbox.
For more information about the System Attendant mailbox, see Issues with the System Attendant Mailbox When Moving an Exchange Mailbox Database.
For more information about moving Exchange mailbox databases, see Moving an Exchange Mailbox Database to Another Server or Storage Group.