I am looking to get going on setting up an Exchange 2010 hybrid for my existing on-premise Exchange 2010 server.
From what I understand, the first step in this process is to setup a new server for Active Directory synchronization with O365, is that correct? Should it be its own server or should I install that on the Exchange 2010 server?
As for the AD sync step, should I configure everyone's AD account UserPrincipalName to match their E-mail address? The reason I ask is because in our forest, there are two domains and potentially duplicate usernames/samaccountnames.
So my understanding about the AD sync is that it might be better to ensure everyone's UPN is unique before starting the sync, and ensuring everyone can login to Exchange Online with their UPN federated domain instead of local.domain\username.