We are in the process of planning and investigating a potential move of our email from a hosted Exchange solutions provider to Office 365 (Exchange Online to be specific). Now the hosted exchange provider have their own AD and therefore our email accounts are not federated with our internal domain active directory. Therefore we have seperate passwords for our AD and Email. Not synced.
Now I have a fair idea of how the migration will go; a cutover batch migration of the users (in our OU on the hosting providers AD) and their corresponding passwords and mailboxes to Exchange Online. A sync every evening to "top-up" mail received during the day and then a final sync before the switch get's flicked.
Now my question is how do we tie the post migration accounts that now will sit on Exchange Online, with our onsite AD accounts and is it possible to do it retrospectively in a sensible user friendly nature?
Thanks for your insights in advance,