Update 6/13/2025: Please see our new blog post for updated timelines of releases as well as additional details on how to get from current versions of Exchange Server to Exchange Server SE: Upgrading ...
Updated Jun 13, 2025
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YoWoo, see Microsoft Exchange Server licensing and FAQ– email for business for details on the Server and CAL licensing model used by Exchange Server 2019. Exchange Server SE will also use the Server and CAL licensing model, but those licenses must be cloud subscription licenses, or licenses with Software Assurance.
4ppl3c0r3, your assumption is incorrect. With Exchange Server SE, if you don't buy cloud subscription licenses, then the licenses you do buy must have Software Assurance (SA). So, you want option 2...buy Exchange 2019 with SA because (1) it gives you next version rights (e.g., licenses for Exchange SE), and (2) as long as you keep your SA active, it satisfies your subscription requirements.