When migrating Exchange mailboxes, Migration Wizard copies directory and mailbox information from the source Exchange server and directory service (Exchange Directory or Active Directory) to the target Exchange 2000 server and Active Directory forest. The steps Migration Wizard performs to accomplish these tasks are based on Active Directory searches.
Migration Wizard searches the target Active Directory for user objects that match the mailboxes selected for migration. For each security identifier (SID) not found in Active Directory, Migration Wizard creates a disabled user object that corresponds to the account you are migrating.
Most matches are based on Windows SIDs. In both Windows NT 4.0 and Windows 2000, each user account has a SID. In addition, Exchange 5.5 uses the SID to associate mailboxes with Windows NT 4.0 user accounts.
If Migration Wizard finds a user object in Active Directory that matches the mailbox to be migrated, Migration Wizard:
If you migrate mailboxes to a new Active Directory forest but you keep the user objects in the current domain or forest, Migration Wizard will not find the appropriate SIDs in the target Active Directory. In this case, Migration Wizard:
Important A trust relationship must exist between the source and target domains to allow the source user object to access its new Exchange 2000 mailbox.
Note The Windows Account Creation and Association screen in Migration Wizard lists the mail accounts you selected for migration. If an existing user object is located in Active Directory, the existing user object's distinguished name is shown in the Existing Windows Account column. If a disabled user object is created for the mailbox account, the disabled user object's distinguished name is shown in the New Windows Account column.
After searching for user objects, Migration Wizard searches Active Directory for contact objects that match the mailboxes selected for migration. When a match is found, Migration Wizard:
The directory information from the contact object is merged with the user object's attributes based on the following rules:
If Migration Wizard does not find any contacts, it considers the search process to be complete (no new objects are created).
For more information about matching, see Selecting Which Accounts to Migrate.