Microsoft has officially launched its new Exchange Server Subscription Edition (SE), marking a pivotal shift from traditional perpetual licenses to a subscription-based model for its on-premises email server. Announced today, the release provides a direct, in-place upgrade path for Exchange 2019 users.
This move establishes the future for on-premises deployments as the October 2025 end-of-support deadline for Exchange Server 2016 and 2019 looms. The new edition signals Microsoft’s long-term strategy for customers who are not yet ready or able to migrate fully to the cloud-based Exchange Online service.
The company had previously indicated a Q3 2025 release, but this general availability arrives earlier, underscoring the urgency for organizations to plan their transition. For many, this provides a clear and necessary path forward for their on-premises infrastructure, ending years of uncertainty.
A New Evergreen Era for On-Premises Exchange
The most significant change introduced with Exchange Server SE is its governance under Microsoft’s Modern Lifecycle Policy. This policy transforms the product into an “evergreen” service, fundamentally altering how it is supported and updated over time, moving away from the old model of fixed lifecycles.
Instead of major version releases every few years followed by a fixed support end date, Exchange SE will receive continuous updates through biannual Cumulative Updates (CUs). According to Microsoft’s Exchange Team, “The product will be serviced continuously as an evergreen release, with no additional major, year-based versions planned for the future release.”
This approach eliminates the need for costly and disruptive “big bang” migrations that admins dreaded, replacing them with a more predictable and manageable servicing schedule. For Microsoft, it creates a steady, recurring revenue stream, while for customers, it promises continuous value and security patches without major upgrade projects.
This strategy aligns Exchange with other enterprise products like SharePoint Server Subscription Edition, which already follows a similar subscription and servicing model. It demonstrates a broader push by Microsoft to standardize its on-premises server offerings under a predictable, modern framework.
The Upgrade Path: A Seamless Transition for Exchange 2019
Microsoft is emphasizing a low-risk, straightforward upgrade process, particularly for organizations currently running recent versions of Exchange Server 2019. The initial Release to Manufacturing (RTM) build of Exchange SE is functionally identical to Exchange 2019 Cumulative Update 15 (CU15).
This parity is key to the low-risk nature of the upgrade. An in-place upgrade from Exchange 2019 CU14 or CU15 is fully supported. Crucially, it requires no Active Directory schema changes, new installation prerequisites, or different license keys for the initial RTM version.
This design minimizes administrative overhead and potential disruption, meaning existing scripts and third-party integrations should continue to function without immediate changes. For organizations still on Exchange Server 2016, however, the path is more involved. They cannot perform an in-place upgrade and must instead build a new Exchange SE infrastructure and perform a classic mailbox migration.
The Clock is Ticking: Sunsetting Exchange 2016 and 2019
The release of Exchange SE carries a significant sense of urgency due to the impending end-of-life for its predecessors. Mainstream support for Exchange 2019 already concluded in January 2024, and the final date for extended support for both Exchange 2016 and 2019 is October 14, 2025.
Microsoft has been unequivocal that it will not offer Extended Security Updates (ESU) for these versions, a critical factor for security and compliance. Running an internet-facing server like Exchange without security patches is a significant risk, making an upgrade essential. After the deadline, Microsoft states, “Exchange SE will be the only supported on-premises version of Exchange.”
This makes migrating to Exchange SE the only viable path for on-premises customers. The company has made it clear that while the initial SE release mirrors 2019 CU15, this will not remain the case. Future CUs, released twice a year, are set to introduce new capabilities and modernizations, which can only happen once the legacy codebases are no longer supported.
Microsoft’s Exchange Team notes that this transition “will create unique opportunities to simplify, streamline, and modernize the product over the coming years,” hinting at significant evolution for the platform once the legacy versions are retired. This move ultimately ensures the longevity of on-premises Exchange, with Microsoft affirming that “Exchange SE demonstrates our commitment to ongoing support for scenarios where on-premises solutions remain critical.”
