How does Exchange Migrator handle conflicting mailboxes?
Exchange Migrator 1.x
Exchange Migrator 2.x
Mailbox Collision Handling
When you migrate a mailbox, Exchange Migrator checks to see if the source mailbox conflicts with a target mailbox. If Exchange Migrator detects a conflict, it applies the collision handling option specified in the migration options wizard to the source object.
A source mailbox conflicts with a target mailbox if it contains an e-mail address, other than X.400, that is also on a mailbox in the target Exchange organization. A source mailbox can also conflict with a target mailbox if it has an alias that matches a mailbox alias in the target site. If there is no conflict with a target mailbox, Exchange Migrator creates a new mailbox on the target server and migrates the source mailbox properties and data to the newly-created target mailbox.