​Microsoft has reminded administrators again that Exchange 2016 and Exchange 2019 will reach the end of extended support next month and has provided guidance for decommissioning outdated servers.

According to the company’s product lifecycle website, Exchange 2016 reached mainstream end date in October 2020, while Exchange 2019’s mainstream support ended on January 9, 2024.

Microsoft also reminded customers in January that Exchange Server 2016 and 2019 will reach the end of support in October.

After October 14, Microsoft will cease providing technical support, including bug fixes for newly discovered issues that may impact the usability and stability of outdated servers.

The company will also stop issuing time zone updates and security fixes for vulnerabilities that may expose servers to security breaches.

“On October 14, 2025, one month from now, Exchange Server 2016 and Exchange Server 2019 will reach end of support. It’s critical to upgrade now to remain supported and secure,” the Exchange Server engineering team warned over the weekend.

“Customer installations of Exchange 2016 and Exchange 2019 will continue to run after October 14, 2025. However, continuing to use these offerings after the end-of-support date invites potential security risks, so we strongly recommend taking action now.”

Microsoft recommends that administrators migrate to Exchange Online (available as a standalone service or as an Office 365 subscription) or upgrade to Exchange Server Subscription Edition (SE).

Admins can perform an in-place upgrade from Exchange Server 2019 to Exchange Server SE, with the process being identical to installing a Cumulative Update (CU).

Those who still have servers running Exchange 2016 and 2013 are advised to upgrade to Exchange Server SE or first install Exchange 2019, respectively.

“If you are running Exchange 2016, we recommend that you perform a legacy (a.k.a. side-by-side) upgrade to Exchange Server SE and do an in-place upgrade to Exchange Server SE when it is available,” Microsoft added.

“ If you still have Exchange Server 2013 or earlier in your organization, you must first remove it before you can install Exchange Server 2019 CU15 or upgrade to Exchange Server SE.”

The company’s documentation site provides detailed Microsoft 365 migration guidance for global admins and can help them decide the best Exchange Online migration path.