Some mailboxes may be merged instead of being cloned during migration in Exchange Server 2003

When you migrate users by running the Microsoft Exchange Migration Wizard in Microsoft Exchange Server 2003, some mailboxes may be merged instead of being cloned. This issue may occur in any one of the following situations:

• You migrate users from a Microsoft Exchange Server 5.5 organization to an Exchange 2003 organization.
• You migrate users from a Microsoft Exchange 2000 Server organization to an Exchange 2003 organization.
• You migrate users from an Exchange 2003 organization in clone mode to a different Exchange 2003 organization.

This issue occurs if all the following conditions are true:

• You canceled a previous instance of the Microsoft Exchange Migration Wizard.
• A mailbox in the destination organization was initialized.
• You ran the migration in clone mode again.

To resolve this issue, locate the mailboxes and the user objects that were successfully migrated before you canceled the migration. Then manually delete the mailboxes and user objects from the Active Directory directory service in the destination organization. After you delete all Active Directory objects that were created by the Exchange Migration Wizard, wait for Active Directory replication to finish, and then start the migration again.

To manually delete the mailboxes and the user objects from the destination organization, follow these steps:

1. Click Start, click Run, type dsa.msc, and then click OK.
2. Expand the domain that you want, and then click Users.
3. In the right pane, right-click the user object that you want to delete, and then click Delete.
4. On the File menu, click Exit.
5. Click Start, point to Programs or to All Programs, point to Microsoft Exchange, and then click System Manager.
6. Expand Administrative Groups, and then expand the administrative group that you want.
7. Expand Servers, and then expand the server that you want.
8. Expand the storage group that you want, and then expand the mailbox store that you want.
9. Right-click Mailboxes, and then click Run Cleanup Agent.
10. In the right pane, right-click the user mailbox that you want to delete, click Exchange Tasks, and then click Next.
11. Click Delete Mailbox, click Next two times, and then click Finish.

The Exchange migration process is actually a copy process. During this copy process, the source mailbox object is not deleted or changed in any way by the migration process. The Exchange Migration Wizard first copies all users and mailboxes to the new organization and then clones the existing data from the source computer.

If you cancel a migration and then run migration again after a mailbox has been initialized, the Exchange Migration Wizard switches to merge mode. A mailbox can be initialized if mail is delivered to the mailbox or if a user logs on to the mailbox. To avoid this situation, you must manually delete all Active Directory objects that were created by the Exchange Migration Wizard, wait for Active Directory replication to finish, and then start the migration again.

For additional information about how to use the Exchange Migration Wizard to migrate mailboxes, click the following article number to view the article in the Microsoft Knowledge Base: