We have purchased Microsoft 365 subscriptions for a few of our users. We are currently using the email exchange of Rackspace.
We have configured Office 365 with the same domain as Rackspace (i.e. a specific user at Office 365 and email address at Rackspace email server are the same "email@example.com")
Is it possible to migrate a few users from Rackspace email server to Office 365 (Microsoft Exchange), whereas all other users remain at the Rackspace email server ?