I have SmarterMail Enterprise 14.2.5704
I need to migrate many big mailbox from Exchange Online to my SmarterMail server.
I would understand with you the proper process to do so.
My aim is to create less disruption as possible to the end user, and especially when I change the settings on the mail client of customer, that this find yourself immediately all mail on mailbox.
If mailbox is small, i dont'have problem.
I set TTL of mx records (customer domain) at a low value, and a few minutes later I migrate the contents of the mailbox with mailbox migration integrated on SmarterMail.
If mailbox is big (20Gb or 50Gb or more), the problem is more complex because it takes time to move / migrate all the content of one or more mailboxes.
I thought of doing a first migration of all the domain mailboxes before changing MX records, then when the migration is complete, change the MX record and redo a migration to copy / move the latest email.
But I think using SmarterMail mailbox migration, this involves duplicating all the emails, right?
If you use IMAP Retrieval I could do as I thought?
Or here you are duplicated emails?
Or I need to use third-party tool for migrate big mailboxes on many steps ?