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With both Exchange 2016 and 2019 going out of support in October 2025, we have heard from some of our customers that they have started their migrations to Exchange Subscription Edition (SE) but might need a few extra months of Security Updates (SU) for their Exchange 2016 / 2019 servers while they are finalizing their migrations.

We are announcing that we now have a solution for such customers. Starting on August 1^st, 2025, customers can contact their Microsoft account team to get information about and purchase an additional 6-month Extended Security Update (ESU) for their Exchange 2016 / 2019 servers. Your account teams will have information related to per server cost and additional details on how to purchase and receive ESUs, starting August 1^st, 2025.

What does this mean?

• This ESU is not an “extension of the support lifecycle” (Microsoft Lifecycle Policy | Microsoft Learn) for Exchange 2016 / 2019. Those servers still go out-of-support on October 14, 2025, and you will not be able to open support cases for them (unless directly related to an issue with a SU released to ESU customers during the ESU period).


• This ESU is a way for customers who might not be able to finalize their migrations to Exchange SE before October 14, 2025, to receive Critical and Important updates (as currently defined by Microsoft Security Response Center (MSRC) scoring) as SUs that we might release after October 2025. If there are SUs that we need to release, we will privately provide such SUs to ESU customers. Exchange 2016 / 2019 SUs will not be released on public Download Center or Windows Update after October 2025.


• We are not committing to actually releasing any SUs during the ESU period. Exchange Server does not necessarily receive SU updates every month on Patch Tuesday (2^nd Tuesday of the month) as SUs are released only if there are Critical or Important security product changes. Therefore, if there are no SUs that we need to release during the time of ESU, there will be no such updates provided. We will, however, confirm with ESU participants each Patch Tuesday whether an SU was provided or not.


• This ESU will be valid for 6 months only (through April 14, 2026). This period will not be extended past April 2026 (you do not need to ask).

Who is Exchange 2016 / 2019 ESU for?

This program is intended only for customers who are unable to finalize their migrations to Exchange SE before end of support lifecycle for Exchange 2016 / 2019, already use Exchange 2016 CU23 or Exchange 2019 CU14/CU15, and still need Critical and Important security coverage for the older servers still in operation.

• We recommend that customers do not rely on this ESU, but instead upgrade their organizations to Exchange SE in time.


• Customers using Exchange 2019 should in-place upgrade to Exchange SE quickly and switch to the Exchange SE modern lifecycle policy.

Please continue migrating to Exchange SE in time instead of taking advantage of this ESU program. But if you really must, please contact your Microsoft account team for more details starting August 1^st, 2025.

A similar program is available for our Skype for Business 2015 / 2019 customers. Please read more here.

The Exchange Server Team