Migration Manager for Active Directory

Migrating only users from Source to Target, leaving Exchange mailboxes on Source.

I am Migrating only Users from Source to Target (MMAD), leaving Exchange mailboxes on Source.

What "Specify Exchange Options" should I select under Synchronization Properties?

-Users without mail options

-Mail-enabled users

-Mail-enabled users for native Move

-Mailbox-enabled users

I just want the Users, after migration to Target Domain to be able to access their mailboxes.

Should I disabled their Source User IDs or would that disabled the mailbox.

Thank you,