Part (1 division about 200 mailboxes) of the company was sold . I need move this company to Exchange Online . I would like to use cutover migration, but is it possible to move only selected 200 mailboxes to new tenant ? It is not possible to use hybrid deployment with ad sync. Migration batch does not allow select mailboxes individually. Is it possible to use migration account which has permission "full access right" only to 200 mailboxes ?
Cutover is "all or nothing" approach, and while you can play with the rules a bit, I wouldn't recommend it. Besides, Hybrid offers a way better experience both for end users and admins alike. If that's not an option, perhaps a third-party tool might be a better choice, as most of those help you with things such as client reconfiguration, etc.