Future-proof with Exchange SE
Everything you need to know about the update and why you should act before it's too late.
With the introduction of the Microsoft Exchange Server Subscription Edition (Exchange SE), Microsoft is ushering in a new era in the Exchange world.
The new Exchange Server Subscription Edition will be launched in July 2025 - a milestone for all companies with a local Exchange infrastructure. Companies will have to react by October 2025 at the latest if they want to continue to receive support, security and updates.
Who is affected?
Relevant for
All Exchange Server versions
Companies that have Exchange Server versions in use.
Relevant for
Local mail servers
IT departments that rely on local mail servers or hybrid structures and have not migrated exclusively to Exchange Online.
Relevant for
Support & Security
organizations, with a special focus on up-to-dateness, support and security.
Dates & deadlines
What will change in concrete terms?
01
End of Support
Support for all Exchange versions except SE will end in October 2025. Anyone who does not switch will be operating an insecure and no longer supported environment.
02
Modern Life-cycle Policy
Support for all Exchange versions except SE will end in October 2025. Anyone who does not switch will be operating an insecure and no longer supported environment.
03
Simplified Hybrid App
The publication of internal SCP (Service Connection Point) URLs will no longer be necessary in future, reducing complexity and potential sources of error during setup. Companies benefit from significantly simplified network configuration.
04
Admin API
The new Admin API is based on modern web standards (REST, JSON, HTTPS, OAuth, Microsoft Graph). It enables the platform-independent connection of external systems, for example for monitoring or administration purposes. It is intended as a long-term replacement for PowerShell and thus forms the basis for modern, secure and automatable administration in hybrid environments.
05
Last release
Future changes will only be made via continuous updates as part of the subscription model - no more classic version changes.
06
No Coexistence
As of SE CU1 (release Q1/2026), there will no longer be any coexistence with old Exchange versions. This makes the planning and implementation of the changeover even more important.
07
Feature Flighting
Enables new functions to be activated selectively after an update - without rebooting and after prior testing.
What do companies need to do now?
Companies should plan ahead instead of switching under pressure. Compatibilities can be tested at an early stage to avoid security and compatibility risks. This also allows you to control your costs and resources.
Inventory
Which Exchange version is in use? Which add-ons and integrations are affected?
Strategy
Direct migration or legacy migration from 2016 to 2019?
Measures
Clarify technical, organizational and time resources.
Implementation
Use the time to start without stress.
You're not sure?We are happy to support you.
Possible paths to Exchange SE
The switch to Exchange Server Subscription Edition (SE) is inevitable - but there are several ways to get there. The important thing is: Not every path is realistic in the given time frame.
Legacy migration from Exchange 2016
Technically possible, with considerable effort.
As Exchange SE will not be released until July 2025 and support for Exchange 2016 will end in October 2025, there is only a very tight timeframe for implementation. The so-called legacy migration from Exchange 2016 to Exchange SE requires the creation of a complete coexistence environment, mailbox migration and the clean decommissioning of the Exchange infrastructure to be replaced. A complex and time-consuming process that is almost impossible to implement on time in many environments.
We recommend
Intermediate step to Exchange 2019 Cu15.
This version already supports Server 2025 RTM and enables a fast, secure and low-risk in-place upgrade from Exchange 2019 to SE RTM at a later date - without the need for time-consuming coexistence.The hybrid configuration should be set up at an early stage and the mail flow should be controlled in a targeted manner to avoid disruptions during the migration and ensure a smooth transition.
Windows Server 2025
Windows Server 2025 is the right long-term choice because it is fully supported by the new Exchange Server SE.
SE RTM already supports Server 2025.
Productive use of Exchange SE on Windows Server 2025 will be possible from October 2025.
Hybrid operation with Exchange SE + Exchange Online
Step-by-step migration with central administration via Exchange SE.
Companies with an existing hybrid configuration to Exchange Online benefit from the ability to migrate their mailboxes in a controlled and uninterrupted manner - without cut-over, without risk.
We recommend
Intermediate step to Exchange 2019 Cu15
The prerequisite for an in-place upgrade to Exchange Server SE is Exchange Server 2019 CU15.
Exchange SE is essential for the long-term maintenance of the hybrid environment and in particular with regard to the Modern Lifecycle Policy.From July 2025, an in-place upgrade to Exchange SE can take place based on this.With CU1 (expected at the end of 2025), the hybrid connection will be made via a dedicated hybrid app - without publishing any internal SCP URLs. This will significantly simplify the network configuration.The migration of user mailboxes can continue to take place gradually - with central management via Exchange SE.
