Update 10/22/2025: Addition of two more FAQs.
In May 2024, we shared our Exchange Server Roadmap Update and our plans for the future of Exchange Server. Since then, we’ve been asked some questions ...
Updated Oct 22, 2025
Version 18.0
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yihch
Microsoft
MicrosoftI am not sure if my understanding is correct. Does the table above mean that Exchange 2016 cu23/2019 cu14&15 will be kept the extended support status until the day Exchange SE cu1 is released and can get corresponding issue support?
I don't think it means that. Instead I believe it means that they will support both being installed in one tenant (I think is the term they generally use) until CU1 is released. If something goes wrong with that interoperation they will fix it. That could mean that the older versions get a patch, but that is unlikely. It does mean that the older version would not get patched for other issues because it is out of support.
After CU1 until CU2, it should continue to work, but they won't guarantee it. Likely they would try to avoid changes that would intentionally prevent that. Once CU2 is released (and installed?) it won't be supported in any way anymore.