Overview
- Microsoft announced a second six-month Extended Security Update window for Exchange Server 2016/2019 and Skype for Business Server 2015/2019, running from May through October 2026.
- Enrollment is not automatic because Period 2 is a separate purchase that customers must make through their Microsoft account teams.
- Any fixes will be delivered privately only to ESU customers and only if Microsoft rates the issues Critical or Important, with no promise that updates will ship during this period.
- For Exchange, Period 2 covers servers on Exchange 2016 CU23 and Exchange 2019 CU14 or CU15, and purchases made after April 15 are placed into this new window.
- Microsoft emphasizes that ESU does not restore normal product support and urges organizations to complete migrations to supported platforms such as Exchange Subscription Edition or Teams.