Exchange Server Subscription Edition (SE) is now available

Let's see if we can give you some answers:

• Yes, you can install Exchange SE directly into a pure Exchange 2016 organization and move the data over (move mailboxes, public folders etc.). Once this is done, decommission Exchange 2016.
• To the best of my knowledge, Exchange SE is already in any price lists that it should be in. Check here for example. That being said – I am not certain if CSP can sell you an Exchange SE license because Exchange SE license requires SA (Software Assurance). I am not certain if CSPs can provide SA.
• Continuing with existing SA is totally fine. See “To summarize your licensing options” in Upgrading your organization from current versions to Exchange Server SE.
• We suggest that you install Exchange SE on the latest Windows Server OS available, to help you extend the support lifetime of the server (because major upgrades of the OS “under” Exchange are not supported). Please see Exchange Server supportability matrix.
• Coming from Exchange 2016, you will have to update schema. Once Exchange SE is installed, you will need to re-run HCW to make the Exchange SE server the hybrid endpoint. DAG membership does not matter, because you cannot add Exchange SE into a DAG with an Exchange 2016 server (this is not supported) so you’ll need to build a new DAG. Edge subscription will need to be redone with Exchange SE.
• Note that before you install your first Exchange SE server, you must make sure that Exchange 2013 is not in the organization (you did not mention if this exists, I am just saying). Exchange SE will block installation if E2013 is present. Also - adding Exchange SE to organization with Exchange 2016 will work but only until Exchange SE CU2 is released (ETA, about a year from now). With Exchange SE CU2, we will block coexistence with E2016/E2019.