Microsoft Ends Exchange 2016 and 2019 Security Updates in October

Microsoft will end Exchange Server 2016 and 2019 Extended Security Updates after October 2026, leaving unsupported servers without further security fixes.

The company confirmed that it will not extend the ESU program again. Organizations still running either Exchange version must upgrade or migrate before the final deadline.

Exchange 2016 and 2019 ESU Support Ends in October

Exchange Server 2016 and Exchange Server 2019 originally reached the end of support in October 2025.

Microsoft continued supplying security updates through its Extended Security Update program. In April 2026, the company extended the program for another six months, giving administrators additional time to complete their migration plans.

That extension will now end permanently in October 2026.

Organizations enrolled in Period 2 of the ESU program will also stop receiving updates once October ends. Microsoft says it will not offer another extension for either Exchange version.

After the deadline, Microsoft will no longer release security updates for Exchange Server 2016 or Exchange Server 2019.

Microsoft Recommends Exchange Server Subscription Edition

Microsoft recommends moving supported environments to Exchange Server Subscription Edition, also known as Exchange SE.

Organizations currently using Exchange Server 2019 can perform an in-place upgrade to Exchange SE. Microsoft describes the process as similar to installing a regular Exchange Cumulative Update.

This upgrade path allows administrators to retain the existing Exchange environment without completing a full server migration.

However, organizations should still review hardware, operating system, licensing and compatibility requirements before starting the upgrade.

Exchange 2016 and 2013 Require Migration

Organizations still running Exchange Server 2016 cannot directly follow the same in-place upgrade path available for Exchange 2019.

Microsoft recommends migrating Exchange 2016 environments to Exchange SE. Administrators may need to move through Exchange Server 2019 first, depending on the existing configuration and migration plan.

Exchange Server 2013 installations also require migration because that version has already moved well beyond its support lifecycle.

Admins should inventory all Exchange servers, connectors, mailboxes, applications and hybrid configurations before beginning the transition.

Organizations that no longer want to maintain on-premises Exchange infrastructure can migrate to Exchange Online.

What Happens After October 2026?

Exchange Server 2016 and 2019 systems will continue functioning after the ESU deadline, but Microsoft will no longer provide security patches.

Microsoft is urging administrators to complete Exchange SE upgrades or Exchange Online migrations before the Extended Security Update program ends in October 2026.

The warning follows several other approaching Microsoft support deadlines. Windows Server 2022 mainstream support will also end soon, while Windows 11 version 24H2 and Windows 10 LTSB 2016 are approaching their own support cutoffs.