Today, October 14, 2025, Exchange Server 2016 and Exchange Server 2019 reach end of support. It’s critical to upgrade now to remain supported and secure.
Microsoft will no longer provide technical ...
Updated Oct 14, 2025
Version 2.0
Blog Post
What are the plans re. transport-based enforcement for customers still using Exchange 2016/2019?
With Exchange 2019 being in scope since February (if I remember correctly), does this mean Exchange online will now start throttling and blocking mails from these servers, with a 100% block in 90 days?
Or is there a separate timeline related to the release of CU's for SE?
- Nino_Bilic
Microsoft
Unknown; we do not have exact date when we plan to start throttling/blocking servers that are fully up to date when E2016/E2019 went out of support. We do not use this as a way to get people to upgrade to Exchange SE. We use it to nudge customers who are significantly out of date, and that definition can change based on what happens in security landscape after E2016/E2019 went out of support. So - there might be reasons to throttle/block E2016/E2019 if they are not on ESU updates before April 2026, but right now we are not planning on doing so.
We typically have a pretty generous number of updates that we do not block, even today, but a significant vulnerability might change our timeline. Either way, when throttling/blocking comes for Exchange 2016/2019 (up to date as of yesterday's updates) - which will happen someday, there will be a standard 90 day process, yes.
