Exchange Server 2016 & 2019 and Skype for Business Server 2016 & 2019 go out of support in October 2025 (4 months at the time of writing).
The new Subscription editions have been announced as Generally Available by Microsoft (although not yet added to the Product Terms) but not all organisations are ready to make the move. To help with that, from August 1st, 2025, customers can contact their Microsoft account teams to purchase a 6-month Extended Security Update (ESU).
What to know
- Any Critical/Important Security Updates released after the end of support will be privately provided to ESU customers.
- Microsoft are not committing to release any updates during the ESU period.
- The ESU will run for 6 months until April 14th, 2026 and – in Microsoft’s somewhat snarky words – “This period will not be extended past April 2026 (you do not need to ask).”
See Exchange details here – https://techcommunity.microsoft.com/blog/exchange/announcing-exchange-2016–2019-extended-security-update-program/4433495
See Skype details here – https://techcommunity.microsoft.com/blog/skype_for_business_blog/announcing-skype-for-business-2015–2019-extended-security-update-program/4433493
Cloudy with a chance of Licensing 