[German]A short note for administrators of Microsoft Exchange Server 2016: Both Microsoft Exchange 2016 and Microsoft Exchange 2019 will reach the end of support in October 2025. Microsoft has published a Techcommunity article with information on "decommissioning Microsoft Exchange 2016" in an environment with Microsoft Exchange 2019. Here a few details and thoughts about that.
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End of support for Exchange 2016/2019 in 2025
It is a strange situation in my eyes: On October 14, 2025, the extended support for Exchange Server 2016 will end and it will no longer be supported by Microsoft from this date (see). Mainstream support has already expired on October 13, 2020. This means that Microsoft will roll out the last security update for Exchange Server 2016 by October 14, 2025 at the latest.
The first thought would be to upgrade to Microsoft Exchange 2019 to have peace of mind again. However, the problem is that Microsoft Exchange Server 2019 will also reach the end of mainstream support on January 9, 2024. And on October 14, 2025, this product will also fall out of extended support, will no longer be supported and will contain the last security update by this date at the latest.
For the second half of 2024, Microsoft still has the cumulative update 2024 H2 (CU15) for Exchange Server 2019 in preparation, which should be rolled out sometime in the coming months. I had reported on this in the article Exchange Server 2019 Mainstream Support ended on January 9, 2024 – but has few consequences.
Administrators of Microsoft Exchange Server 2016 are now faced with the question of how to replace this product. Microsoft Exchange Server 2019 will also cease to be supported in a year's time, in October 2025, and a successor is not yet available.
Notes on the decommissioning of Exchange 2016
Microsoft recommends migrating from Exchange 2016 to Exchange Server 2019 and published instructions for replacing old Exchange 2016 installations a few days ago. Jeff Wolsey, Principal Program Manager at Microsoft for Azure Stack HCI/Windows Server/Hybrid Cloud, refers to the Techcommunity article Decommissioning Exchange Server 2016 in the following tweet.
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When I read the first reports, I was briefly confused, as I initially thought that Exchange 2016 would reach the end of support in two months (on October 8, 2024, like Windows 11 21H2 and Windows 11 22H2 Home and Pro). But a check showed that the above information that both currently available and still in support Microsoft Exchange Server versions 2016 and 2019 will fall out of support in October 2025.
Why then Microsoft's post above referring to Microsoft Exchange Server 2016 end of support on October 14, 2025? The reason:
- Only systems with Exchange Server 2019 support a direct upgrade via in-place upgrades to the next version, the Exchange Server Subscription Edition (SE).
- For Microsoft Exchange Server 2016, there is no in-place upgrade to the successor, Microsoft Exchange SE, Microsoft recommends switching to Exchange 2019.
Therefore, Microsoft points out in the Techcommunity post that the Microsoft Exchange Server 2016 installations in an environment with Microsoft Exchange Server 2019 installations must be decommissioned at some point before the end of support.
If administrators want to stay with Exchange on on-premises solutions, Microsoft recommends switching to Exchange 2019 as soon as possible. Information on upgrading to Microsoft Exchange Server 2019 can be found here and here.
The Techcommunity article linked above therefore focuses on the questions regarding the removal of Exchange 2016 from an environment in which Exchange 2019 has already been set up. Administrators will find steps in the article on what specifically needs to be checked and considered before Microsoft Exchange Server 2016 is decommissioned after a test phase.
What Microsoft didn't told
Well, the Techcommunity article Decommissioning Exchange Server 2016 has been published on August 8, 2024. While it's good to know, what Microsoft suggests, there are some aspects, that hasn't been told by Redmond – German blog readers pointed that out.
First of all, it's an odd situation, that Microsoft recommend, switching from Exchange 2016 to Exchange 2019 – because both reaches end of life in October 2025. This means in worst case: Buy a license for Exchange 2019 for a few months and then upgrade to Exchange Server SE with another license.
Some users pointed out, that Exchange 2019 will run for 180 days without a license key. And it should be possible, to buy a Exchange SE (SE stands for Subscription Edition) license via software assurance (SA) and use the downgrade right to run Exchange 2019 for a while until upgrading to Exchange SE.
Running Microsoft Exchange Subscription Edition (SE) requires Windows Server 2022 or later, due to TLS 1.3 support (afaik). And a word about "why an inplace-upgrade" to Exchange SE is supported in Microsoft Exchange Server 2019. Microsoft has explained that in May 2024 in the Techcommunity article Exchange Server Roadmap Update:
To allow for rapid adoption and deployment, the RTM release of Exchange Server SE will be code equivalent to (e.g., the same exact code as) Exchange Server 2019 CU15, except for the following changes:
- The License agreement, an RTF file shown only in the GUI version of Setup, will be updated.
- The name will change from Microsoft Exchange Server 2019 to Microsoft Exchange Server Subscription Edition.
- The build and version number will be updated.
So in other words: Exchange Server 2019 CU15 is code equivalent with Exchange Server SE – only the name, the license agreement, the build and the version number will be changed/updated.
Microsoft says: "The fastest and easiest way to get from Exchange Server 2019 to Exchange Server SE is to perform an in-place upgrade. The upgrade experience is identical to installing a CU. " But Microsoft says also:
Exchange Server SE also supports legacy upgrades, which involve building out a new infrastructure and moving namespaces and mailboxes to that new infrastructure. Some of these processes are used in other scenarios, such as when replacing server hardware or when you want to use a newer version of Windows Server, and those processes continue to be supported in Exchange Server SE.
If your organization is running Exchange 2016 today and you want to continue to run Exchange on-premises, then you have at least one more legacy upgrade to do.
Microsoft's argument is therefore: "To ensure a timely move from Exchange 2016 to Exchange Server SE, we recommend doing a legacy upgrade now from Exchange 2016 to Exchange 2019 as soon as possible. Once you are running Exchange 2019, you can do a quick and easy in-place upgrade to Exchange Server SE."
Similar articles:
Exchange Server 2019 Mainstream Support ended on January 9, 2024 – but has few consequences
Exchange 2016/2019 get HSTS support; Extended Protection will also be enabled soon
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I don't think there is a single organization that installs any MS product not tested on the date of release. This is at least a year, rather two.