Subscription Edition | Jaap Wesselius

Today, July 1st, 2025, Microsoft released Exchange Server Subscription Edition (SE) as the successor of Exchange Server 2019.

Exchange Server SE in itself is not that exciting, it is 100% binary compatible with Exchange 2019 CU15 with the latest May 2025 Hotfix Update, except for the license agreement (EULA) and the build and version number.

This makes it very easy to do an in-place upgrade from Exchange 2019 CU14 or CU15, or a regular migration where Exchange Server SE is installed in an existing Exchange 2016 environment. Please note that Exchange Server SE cannot be installed in an existing Exchange 2013, just like Exchange 2019 CU15.

The last couple of months I did several presentation on Exchange Server SE and did several project to prepare for Exchange Server SE. The most asked question was “what about the subscription?”.

That’s not too difficult. The subscription is in the license, not in the product. The perpetual license has been discontinued and replaced with a subscription license. As for Exchange Server SE, there’s no online license checking or revocation (for now), and there’s still no need to connect your Exchange SE servers directly to the Internet (but it has some advantages, especially for services like the EEMS or the Feature Flighting service).

Why is this an important update and important timing? On October 14, 2025 which is less than four months from now, Exchange Server 2016 and Exchange 2019 will reach end-of-life and will no longer be supported by Microsoft. These products will of course continue to run, but Microsoft will no longer release any security updates for both products.

If you are still running on an older version of Exchange Server, you are running out of time and you must start an upgrade project soon and upgrade to Exchange 2019 CU14/CU15 of Exchange Server SE when possible.

More information regarding Exchange Server SE can be found here Exchange Server Subscription Edition (SE) is now available and can be downloaded from the VLSC or the Microsoft download center.

Today Microsoft silently released an update to their Exchange roadmap, which includes information regarding Exchange 2019 CU15 and Exchange vNext. You can read all the Microsoft marketing stuff on the Exchange Server Roadmap Update article.

What’s new is that vNext is rebranded to Exchange Server Subscription Edition, just like we have Sharepoint Subscription Edition.

The most important part about Exchange Server Subscription Edition is that it is ‘code equivalent’ to Exchange 2019 CU15. So, if you have Exchange 2019 CU15 running later this year, then updating to vNext is just a matter of an in-place upgrade. There’s one thing we need to look out for, the underlying Operating System. If you install CU15 on Windows Server 2022 (or worse, on Windows Server 2019) and SE only supports Windows Server 2025 we will be very unhappy 🙂

What are new features in Exchange 2019 CU15 and thus Exchange Server SE?

Support for TLS 1.3 (which was planned for CU14).
Certificate management in the Admin Center.
Removal of the UCMA (makes sense, since there won’t be any support for Unified Messaging.
Removal of the MSMQ components in the setup application (MSMQ components are not needed in earlier versions of Exchange 2019, please check the Exchange 2019 requirements article).
Re-introducing certificate management in the Admin Center.

So, when can we expect Exchange Server Subscription Edition? As Exchange Server SE is identical to Exchange 2019 CU15 (in will include the necessary security updates of course) the only difference is the licensing of Exchange Server SE. You need a subscription license for the server, and old Client Access Licenses are no longer supported and you can use the regular Office 365 licenses for clients.

Microsoft states it will be available early Q3 2025, which means early July 2025. Since support for Exchange 2016 and Exchange 2019 will end in October 2025 Microsoft cannot afford to slip this date since you need sufficient time to upgrade from earlier versions of Exchange server.

What’s also interesting is that Microsoft is already releasing information about Exchange Server SE CU1, which should be released by the end of 2025 (can slip though).

The most interesting features in Exchange Server SE are Kerberos authentication for server-to-server authentication, the removal of Outlook Anywhere and the deprecation of Remote PowerShell. This brings Exchange server SE nicely inline with Exchange Online.

There’s one very important announcement Microsoft makes: Exchange server SE CU1 will stop supporting co-existence with ALL PREVIOUS VERSIONS of Exchange server. So, this means that in that timeframe, only Exchange Server SE CU1 (and later) will be supported and all previous versions of Exchange server must be removed from your environment.

Exchange Server SE is still approx 18 months away from now, but it is time to start thinking about your Exchange environment. Do you want to fully move to Exchange Online, or do you want to keep mailboxes on-premises in Exchange Server? If so, it’s time to start working on moving to Exchange 2019 CU14 and upgrade to CU15 later this year (or skip CU14 and move directly to CU15).

It is not a strange idea, I’m currently working with three large Exchange 2016 on-premises deployments to move them to Exchange 2019 and prepare for Exchange server SE.

So, lots of work to do the upcoming 18 months 🙂