Exchange, Skype Servers Get Barely Extended Security Updates

IT staff looking at monitors — Credit: Microsoft

Some customers will be able to buy access to critical security updates for obsolete versions of Exchange Server and Skype for Business Server starting August 1, 2025. The just-announced Extended Security Updates (ESUs) programs for Exchange and Skype for Business reduce risk for customers migrating to Exchange Server SE and Skype for Business Server SE, which will soon be the only supported versions of those on-premises servers.

The following versions are eligible for ESUs:

Exchange Server 2016 CU23

Exchange Server 2019 CU14 or CU15

Skype for Business 2015

Skype for Business 2019.

All of those versions leave product support on Oct. 15, 2025. Microsoft had said it would not offer any support for these Exchange and Skype for Business versions after that date, and was strongly urging customers to treat Oct. 15 as an absolute (while admittedly tight) deadline for migration. Microsoft is still urging but also hedging by offering access to critical security updates through Apr. 14, 2026, via ESUs.

How the Exchange, Skype ESUs Are Different From Other ESUs

Exchange and Skype ESU licenses and media will not ship the same way as Windows, Windows Server, and SQL Server ESUs. Instead, Exchange and Skype for Business customers must apply for the ESU programs through their Microsoft account team (who will provide pricing details) starting Aug. 1, 2025. Microsoft does not specify which customers are eligible, but they must not be able to finish migrating before Oct. 15. And they must be big enough or important enough to have a Microsoft account team assigned.

Importantly, these are brief ESUs – only for six months – and there’s no guarantee there will be any Critical or Important security updates to release; the program is “just in case” insurance. Also, Microsoft claims the ESU period won’t be extended, saying “you don’t need to ask.” But they were adamant that support for those older versions would end in Oct. 2025, too.