Marking a new era for the on-premises Exchange Server, Microsoft had officially announced the launch of the Exchange Server Subscription Edition (SE) on July 1, 2025. The new successor of the Exchange Server brings some new features and changes to the way the on-premises server is licensed and serviced. Unlike previous Exchange Server versions, the new SE version will be governed by Modern Lifecycle Policy, which means that there will be no fixed end date for support and there will not be any new versions of Exchange Servers but a continuous servicing and upgrading of the same version. Let’s see what the changes are and what’s new in the Subscription Edition.
What are the major changes?
The major change is the deprecation of the older Exchange Servers. The supported versions, which currently are Exchange Server 2016 and 2019, can coexist with the new Exchange Server Subscription Edition Release to Manufacturing (RTM), until the first Cumulative Update for SE is released. After that, no coexistence is possible. The support for both the Exchange Servers will end at the same time in October this year. This means that until October, you will have to invest and plan the migration and sunset the project of any Exchange Server 2016 or 2019.
Here are some of the major changes:
- No more version releases.
- Support for coexistence will end in October 2025.
- Exchange Server 2016 and 2019 will go out of support together.
- Exchange Server Subscription Edition will be the only supported on-premises solution.
What will Exchange Server Subscription Edition Bring?
Before installing an Exchange Server Subscription Edition along with Exchange Server 2016 or 2019, you must make sure that the latest Cumulative Updates (CU) are installed on your existing server. With the latest Cumulative Update (CU) 15 for Exchange Server 2019, you will notice that there are no changes as both instalments are the same for the Release to Manufacturing (RTM).
Microsoft has also released the Skype for Business Server Subscription Edition (SE) with the new edition. There is no change in the licensing for hybrid setups. Similar to the other versions, Subscription Edition (SE) will also offer the free license.
Previously, you need to buy the server license and then the Client Access Licenses (CALs), depending on the number of users. For the Subscription Edition (SE), you still need to purchase the server license but for the user CALs, you need to maintain an active subscription. This means that you can purchase only with one of the below models:
- Microsoft 365 cloud subscriptions for all the users, including Microsoft 365 E3 or E5 licenses. This means that any user accessing the Exchange Server must have a Microsoft 365 license.
- An Exchange Server Subscription Edition (SE) license and the user CALs with Software Assurance (SA).
How to Upgrade to Exchange Server Subscription Edition?
You have the option for coexistence with Exchange Server Subscription Edition until October 2025 when both Exchange Server 2016 and Exchange Server 2019 go out of support, and the Cumulative Update (CU) 1 for the Subscription Edition (SE) is released.
If you have an Exchange Server 2013 in your environment, then you need to decommission it before introducing the Subscription Edition (SE) as it is not supported.
Before going for upgrade, you should make sure that the Exchange Server 2016 is installed with the Cumulative Update (CU) 23 and Exchange Server 2019 is installed with the Cumulative Update (CU) 14 or 15.
Moreover, upgrading to Exchange Server Subscription Edition (SE) will be a low risk task. This is because the Release to Manufacturing (RTM) version is essentially built on top of Exchange Server 2019 Cumulative Update (CU) 14/15.
The migration to Exchange Server Subscription Edition is also similar to the legacy and current versions. You need to perform the following steps:
- Install the new server side-by-side with the current infrastructure.
- Move mailboxes to the new server.
- Create the connectors on the new server.
- Make sure that the certificates are copied.
- Make the necessary changes on the router to route traffic to the new server.
- Decommission the current Exchange Server.
Final Thoughts
Now, the Exchange Server Subscription Edition has officially been released, you can upgrade to the new version before the end of support for Exchange Server 2016 and Exchange Server 2019. However, planning is crucial either you have a standalone server or a Database Availability Group (DAG) as you would end up with issues during migration, resulting in disruption of the services. Ensure that there are no immediate backup issues. So, check with your supplier and make sure the backup application is fully supported and aware of the new version. Since the Cumulative Update (CU) for the Subscription Edition is scheduled for October, you have ample time to plan and prepare for the migration.
