Microsoft Extends ESU Program for Legacy Exchange and Skype Systems

Severity: Low (Score: 36.9)

Sources: Petri, techcommunity.microsoft.com, Theregister

Summary

On April 16, 2026, Microsoft announced an extension of its Extended Security Update (ESU) program for legacy Exchange Server and Skype for Business versions, providing critical security updates for customers unable to migrate to supported versions. This second phase of the ESU program will run from May 2026 to October 2026, offering a temporary safety net for organizations still operating Exchange 2016 or 2019. Customers must purchase this extension separately, as enrollment is not automatic, and Microsoft has emphasized that there will be no further extensions beyond this period. The updates will not be available through Windows Update or public download channels and will be delivered directly to enrolled customers. Microsoft has reiterated that this program is not a long-term solution and encourages customers to complete their migrations as soon as possible. The announcement reflects Microsoft's acknowledgment of the challenges faced by some customers in transitioning to newer products. Key Points: • Microsoft has launched a second phase of the ESU program for legacy Exchange and Skype systems. • The new ESU phase runs from May 2026 to October 2026 and requires separate purchase. • Microsoft warns there will be no further extensions beyond this second phase.

Key Entities

• onmsft.com (domain)