Azure AD Connect sync with existing Office 365 tenant with active accounts

[Gurdev Singh]

Has anyone ever setup AAD Connect to sync with an existing Office 365 tenant and share their learning. We have an existing Office 365 tenant where all users have been created as cloud only, has Office 365 E3 licenses assigned and Exchange Online used for email. End users have different UPN in on-premises AD and AAD.

We are particularly concerned about Exchange Hybrid requirement that an exchange on-premises server is required in order to change mail related properties of synced objects. Given company migrated their exchange on-premises to Exchange online few years ago and there are no exchange on-premises servers any more. Would setting the sync now also require to re-configure Exchange hybrid again.

[#2]

That's not an Exchange Hybrid requirement per se, *every* configuration involving managing Exchange-related attributes has the same dependency. The reason being, the only *supported* tool to manage Exchange-related objects and attributes are... the Exchange management tools! Now, if you don't care about the *supported* part, you can just as easily manage them via the AD tools instead.