What is Exchange Server SE? Since July 1, 2025, Exchange Server Subscription Edition (SE) has been the only on-premises Exchange version that Microsoft continues to develop. Technically, the first release corresponds to Exchange Server 2019 with Cumulative Update 15. Two things have changed: there is no fixed end of support and there are no more year-numbered versions, and Microsoft permanently requires active Software Assurance or matching cloud subscriptions for servers and CALs. Microsoft does not provide for a pure one-time license without an ongoing agreement for SE.
Quick decision
| Your situation | What this means for you |
|---|---|
| Exchange 2019 with CU14 or CU15 | direct upgrade to SE like a cumulative update |
| Exchange 2016 | set up new SE servers and move the mailboxes |
| Exchange 2013 or earlier | first migrate to Exchange 2019, remove 2013, then move to SE |
| Fewer than 25 mailboxes, no need for your own server | consider Exchange Online; your own server means hardware, maintenance and ongoing agreements |
| Your own server is mandatory (regulations, line-of-business applications, data residency) | plan for Exchange Server SE with Software Assurance |
What happens to the old versions is covered in the guide
Exchange 2016 and 2019: end of support and options.
What changes and what does not
| Topic | Exchange Server 2019 | Exchange Server SE |
|---|---|---|
| Lifecycle | fixed, support ended on October 14, 2025 | continuous (Modern Lifecycle Policy), no fixed end date |
| Committed support | – | at least until December 31, 2035 |
| New major versions | every few years with a year number | none anymore, only cumulative updates |
| Updates | cumulative updates and security updates | two cumulative updates per year, security updates as needed |
| Licensing model | server license + CALs | server license + CALs |
| Additional condition | none | active Software Assurance or qualifying cloud subscriptions |
| Editions | Standard (up to 5 mailbox databases), Enterprise (up to 100) | unchanged |
| Server roles | Mailbox, Edge Transport | unchanged |
| Operating system | Windows Server 2019, 2022, 2025 | Windows Server 2019, 2022, 2025 |
According to Microsoft, the first release of SE (RTM) differs from Exchange 2019 CU15 in only four points: the license agreement in Setup, the product name, the version number and the security updates released up to then. No features were added and none were removed, the Active Directory schema stayed the same, and no new product keys were needed.
The update roadmap
| Release | Date according to Microsoft | Meaning |
|---|---|---|
| Exchange 2019 CU15 | released | last cumulative update for 2019 |
| Exchange SE RTM | July 1, 2025 | renaming and new lifecycle, no new features |
| Exchange SE CU1 | second half of 2026 | first new features |
| Exchange SE CU2 | first half of 2027 | further development |
| Exchange SE CU3 | 2027 | Setup refuses the installation as long as Exchange 2013, 2016 or 2019 is in the organization |
The table reflects the version of the Microsoft post dated October 27, 2026. In the list of build numbers, Microsoft did not yet list a CU1 on November 10, 2026. Microsoft has also announced that later updates will require separate product keys for SE.
Important for planning: if you run SE alongside Exchange 2016 or 2019, you must decommission the old servers before CU3. Otherwise SE can no longer be updated after that.
How Exchange Server SE is licensed
Every Exchange administrator knows the basic model:
- Server license per running instance, whether on a physical server or in a virtual machine. Standard manages 1 to 5 mailbox databases, Enterprise 1 to 100.
- Standard CAL per user or device that accesses Exchange. It is always required.
- Enterprise CAL as an add-on to the Standard CAL for advanced features such as the archive mailbox and holds. The difference is explained in the guide Exchange CAL Standard or Enterprise.
- According to Microsoft, external users need no CALs; their access to the standard features is covered by the server license.
What is new is the condition of an ongoing agreement. Microsoft names two ways:
- License plus Software Assurance (SA): server licenses and CALs with active SA. This also applies to existing licenses for Exchange 2016 or 2019 as long as their SA is running. SA is a maintenance agreement from Microsoft that is paid annually.
- Cloud subscriptions: all users who access the server have a qualifying subscription, for example Microsoft 365 E3 or E5. Licenses for Exchange Online Plan 1 or 2 replace the CAL here.
Without active SA or a matching subscription, Microsoft’s terms do not allow you to run SE, and you receive no cumulative updates. There is no technical lock: SE does not check the license online. Once a valid product key has been entered, no further checks take place.
The Outlook application is not included in any Exchange CAL. The Standard CAL entitles access through Outlook on the web and through mobile devices with Exchange ActiveSync.
Upgrade paths
From Exchange 2019 (CU14 or CU15): you install SE like a cumulative update over the existing installation. This also works for servers in a database availability group (DAG). You first update older builds to CU15.
From Exchange 2016 (CU23): there is no direct update. You add new SE servers to the organization, move the mailboxes and remove the old servers. Microsoft advises migrating directly to SE and no longer setting up new Exchange 2019 servers.
From Exchange 2013: SE Setup refuses the installation as long as Exchange 2013 is present in the organization.
The operating system cannot be upgraded underneath an installed Exchange. If you want to move from Windows Server 2019 to 2025, you build a new server. The rules for its license are in the guide
Licensing Windows Server: cores.
Typical cases
Tax office, 20 mailboxes, Exchange 2019 on its own hardware, no Software Assurance. Support for 2019 has expired. For SE you would need licenses with SA or subscriptions for all users. Compare this with Exchange Online: there, hardware, the Windows Server license and the upkeep of the server are no longer needed.
Manufacturing company, 180 mailboxes, Exchange 2019 with running SA. You upgrade directly to SE. The existing licenses remain valid as long as the SA stays active.
Public administration, 400 mailboxes on Exchange 2016, data must stay in-house. Plan new servers on Windows Server 2025, the migration of the mailboxes and the licenses with SA. The old servers must be removed before CU3.
At VivaKeys
We do not carry the Subscription Edition, neither server licenses nor CALs. For existing environments we carry client access licenses for the previous version:
- Exchange Server 2019 Standard 1 User CAL and 1 Device CAL
- Exchange Server 2019 Enterprise 1 User CAL
Support for Exchange Server 2019 ended on October 14, 2025. These CALs therefore only make sense to extend an existing environment for the transition period. For access to SE, Microsoft’s terms accept them only with active Software Assurance.
Write to us before you order if you are unsure. All offers are in the
Exchange Server and
CALs categories. The licensing models of the database next to it are explained in the overview
Licensing SQL Server: per core or server + CAL.
Frequently asked questions
Do I need a separate CAL for Exchange Server SE? Yes. Every user or device needs a Standard CAL for Exchange Server SE or an equivalent license, such as Exchange Online Plan 1 or 2. CALs for Exchange 2019 are sufficient only as long as they are covered by active Software Assurance.
Is the Exchange Server SE CAL available as a user CAL and as a device CAL? Yes, Microsoft offers the Standard and the Enterprise CAL each for users and for devices. If several people share one workstation and do not access Exchange otherwise, one device CAL for this device is enough.
What does an Exchange Server SE CAL cost? Microsoft states no prices in its licensing information. We do not carry the Subscription Edition and cannot make an offer for it.
Is Exchange Server SE a subscription? The name does not mean that the server is rented monthly. Licenses with Software Assurance remain perpetual licenses. However, Microsoft requires that the SA or a qualifying subscription stays active as long as you use SE.
Is there an alternative to the Exchange CAL? Yes. According to Microsoft, licenses for Exchange Online Plan 1 or 2 replace the CAL for the on-premises server. If you use Microsoft 365 anyway, you then need no separate CALs.
How long is Exchange Server SE supported? There is no fixed end date. Microsoft has committed that support will end on December 31, 2035 at the earliest. The prerequisite is that you keep the servers up to date.
Sources
Checked on 2026-11-10 against the publisher’s information:
- techcommunity.microsoft.com/blog/exchange/exchange-server-subscription-edition-se-is-now-available/4424924
- techcommunity.microsoft.com/blog/exchange/upgrading-your-organization-from-current-versions-to-exchange-server-se/4241305
- learn.microsoft.com/en-us/exchange/new-features/new-features
- www.microsoft.com/en-us/microsoft-365/exchange/microsoft-exchange-server-licensing-licensing-overview
- www.microsoft.com/en-us/microsoft-365/exchange/microsoft-exchange-licensing-faq-email-for-business
- www.microsoft.com/licensing/terms/productoffering/ExchangeServer/MCA
- learn.microsoft.com/en-us/lifecycle/products/exchange-server-subscription-edition
- learn.microsoft.com/en-us/lifecycle/additional-support-server-modern-lifecycle-policy
- learn.microsoft.com/en-us/exchange/plan-and-deploy/supportability-matrix
- learn.microsoft.com/en-us/exchange/new-features/build-numbers-and-release-dates