In Exchange 2000 Server Service Pack 1 (SP1), a
Migrate from Microsoft Exchange 5.5 option is available. You can also migrate a user account from a command line. If you migrate a user account to Active Directory with a tool such as the Active Directory Migration Tool (ADMT), and then give that user account an Exchange 2000 mailbox, command-line migration may not work, and the following warning and error messages may be logged in the Exchange 2000 Application event log:
Event Type: Error
Event Source: MSExchangeMig
Event Category: None
Event ID: 13002
Date: 2/19/2001
Time: 6:44:25 PM
User: N/A
Computer: server_name
Description: A mailbox could not be found in the target directory with the address 'smtp:user@domain.com'.
Event Type: Warning
Event Source: MSExchangeMig
Event Category: None
Event ID: 15000
Date: 2/19/2001
Time: 6:44:13 PM
User: N/A
Computer: server_name
Description: The mailbox for user 'user' already exists, and may have been created during a previous migration. Check for duplicate mail.