I'm having some trouble understanding how to perform a staged migration while still allowing users to use their Outlook client during their mailbox migration.
I migrated a test mailbox that is roughly the size of our user mailboxes (3GB) and it took 14 hours. During the migration the TargetAddress worked properly and new mail was sent to the cloud, but since AutoDiscover in the domain wont point to the cloud mailbox until after I convert the mailbox-enabled user to a mail-enabled user (a step it appears I can't perform until the migration is complete) the user remains connected to their on-premise mailbox and doesn't receive any new email.
We are basically a 24-hour shop and users receive emails all day and night and need to access those emails without experiencing a significant dealy. Isn't there a way to perform the migration and minimize the disruption to our users?
I wondered if maybe we could remove the TargetAddress from user's AD record during the migration and then after the initial synchronization, we could add the TargetAddress back to the user's AD record and then perform another synchronization to pick up anything that may have changed in their mailbox since the initial synchronization. I would assume that a subsequent synchronization would take significantly less time than the initial synchronization allowing us to start the subsequent synch (with the TargetAddress correctly set) then mail-enable the user. Is something like that possible?