On October 14, 2025, 9 months from today, Exchange Server 2016 and Exchange Server 2019 reach end of support. After October 14, 2025, Microsoft will no longer provide technical support for problems t...
Updated Jan 23, 2025
Version 3.0
Blog Post
I've read this article, the "roadmap" article, and the "upgrading" article multiple times and I want to make sure that I understand what I've read:
1. Historically, extended support has included security patches; however, this is no longer the case. As of October 14, 2025 - MS will only provide case-based tech support to legacy Exchange after this date. Is this correct? (In my company, this means that the software either needs to be upgraded or removed)
2. If I recall correctly, when an Exchange server is Hybrid, CU/HUs must be installed 30 after their release to be supported by MS. So...if the RTM version of SE is released in August, this means that existing hybrid servers must be upgraded by September. Then when the HU is released "in late 2025", we have 30 days to upgrade - which also blocks co-existence with previous version. Because all of my on-prem servers are hybrid, they all have to be decommissioned by that time (or sooner because of no new security patches).
3. For those of us who are running E2019 on its original hardware & have been planning on the extended support period to work the upgrade process as we have with every previous version of Exchange (budgeting, building, jet stress testing, migration, etc.) we will have ~3 months to install, migrate, and decommission existing servers by the October 14th date because there is no way that my security leadership will allow an application to exist on the network where the vendor isn't maintaining its security. I'm curious if others have concluded that this will be their timeline as well.
- Nino_Bilic
Microsoft
1. Exchange 2016 has been in Extended support since October 13, 2020 and Exchange 2019 has been in Extended Support since January 9, 2024. In other words – there was no change in extended support; both Exchange 2016 and 2019 have been getting security updates since they entered Extended support.
2. This is essentially correct, yes. Note that the “running the latest CU” in hybrid applies to the server that is used as a hybrid endpoint in your organization. Not all servers in your organization are “hybrid servers”. Indeed, they are all running in hybrid mode, but they do not all automatically fall under the “should only run the latest CU” for support. But you are correct, that once Exchange SE CU1 is released, that (as currently planned) coexistence with older versions would be removed.
3. As mentioned before, Exchange 2019 has been in Extended support for a year now. That support will end in October 2025. We have been asking our customers to, if they need to install new hardware, install Exchange 2019 on new hardware as we are enabling an upgrade from Exchange 2019 to Exchange Server SE RTM as a “Cumulative Update” upgrade. In other words. All that you’ll need to do is install a new Exchange 2019 CU (let’s call it “CU16” even though it will be called “Exchange Server SE RTM”). Exchange SE RTM will have no new features when compared to Exchange 2019 CU15, but it will switch you to a ”supported” path.
