Mailboxes should not be manually moved (using native Microsoft methods) between information stores during the migration, as it can potentially cause serious issues. See Resolution section for more details.
When a mailbox is moved from one store to another using native Microsoft methods, the "targetAddress" attribute is cleared on the user of the mailbox. This disrupts the mail flow set up by the tool, and can cause serious issues including source users not receiving mail from target users.
If this has already occurred, run a full Directory Synchronization Agent (DSA) re-sync. This will re-populate the attribute and restore mail flow, but will not correct problems such as mail arriving in the target mailbox of un-switched users, etc. This problem must be corrected using tools such as Exmerge, for example.
If you need to move target mailboxes that are involved in a sync job, change the collection properties in QMM to point to another store, and QMM will move the mailboxes.
According to Microsoft KB article ID 297393 "How To Pro-grammatically Move an Exchange Mailbox Using CDOEXM in Visual C++": http://support.microsoft.com/?kbid=297393
The IMailboxStore method, MoveMailbox, performs two sets of tasks as follows:
- Directory-related tasks on the user object
- Updates the homeMTA attribute.
- Updates the store's distinguished name on the homeMDB attribute.
- Deletes the target e-mail address for the user object stored in the targetAddress attribute. This will be updated by the Recipient Update Service (RUS) when it runs against this user.
This means that if the unused mailbox (source mailbox for switched user or target mailbox for unswitched user) is being moved, redirection will temporarily break.
The targetAddress attribute will be restored by the DSA if the users are still in the scope of synchronization but only if there was a change in the source. If source account was not modified then the DSA will not synchronize this account. Knowing this, a resynchronization for some accounts can be triggered by modifying any of the attributes in the source. This can also be done using a scripting approach. If many mailboxes were affected then full resynchronization is a good idea, it will re-populate the targetAddress attribute.
Please note that if the mailbox is still a part of the active collection, Mail Target Agent (MTA) will move the mailbox to the store specified in the collection properties.
More detail on this please see solution SOL15440 - Moving Target Mailboxes in the Middle of Mailbox Sync Job - https://support.quest.com/SUPPORT/index?page=solution&id=SOL15440
