Set up hybrid

[AtanasM]

Currebtly there are are mailboxes on prem as well as in Exchange Online.
How to set up a hybrid with AD connect tool, so that the mailboxes remain only on prem?
What is the best way to do this, when syncing the users, deactivating the EXO mailboxes and without losing any data there?
I need detailed steps, especially how to deactivate EXO mailboxes and sync the on prem mailboxes with the users.

[#2 · Accepted solution]

What you want to do is referred to "offboarding", and with Hybrid in place it's almost the same process as moving mailboxes to ExO: https://docs.microsoft.com/en-us/exchange/hybrid-deployment/move-mailboxes#move-exchange-online-mail...

If you want a more detailed description on how the process works in general, refer to this article series from Steve: http://techgenix.com/migrating-standalone-office-365-tenant-exchange-2010-part1/

It's a bit outdated by now, but the overall process is more or less the same.