Extended Security Update (ESU) Program Announced for Exchange 2016 and 2019

On July 15, 2025, Microsoft shared a new announcement that closely concerns Exchange Server 2016 and 2019 users. This announcement is especially critical for organizations that have not yet completed the migration process. Exchange 2016 and 2019 will be out of official support as of October 14, 2025. However, Microsoft is offering a limited-time solution for customers still in the migration process: the 6-Month Extended Security Updates (ESU) Program.

What is the ESU Program?

ESU is a program designed to provide only critical and important security updates to Exchange 2016 and 2019 servers after support ends. This program includes only updates identified as "Critical" and "Important," according to Microsoft's MSRC system for rating security vulnerabilities.

ESU is not a support extension. Technical support requests will not be accepted under this program. Only security updates will be provided as they become available.

Program Start and End Dates

Updates will be provided exclusively to customers enrolled in the ESU program.

It will not be released via Windows Update or Microsoft Download Center.

On “Patch Tuesday,” the second Tuesday of each month, ESU customers will be specifically notified whether an update has been released for that month.

Microsoft doesn't guarantee that it will release an update during this six-month period. Unless there's a security vulnerability, a Security Update (SU) may not be released.

Who Can Benefit?

Be using Exchange Server 2016 CU23 or Exchange Server 2019 CU14/CU15

Having a plan to transition to Exchange SE but not being able to complete this transition by October 14, 2025

Need for security updates

Migrating to Exchange SE is the ideal and recommended solution. ESU is a short-term migration solution only for emergencies.

Customers who wish to participate in the ESU program must contact their Microsoft account manager by August 1, 2025.