Exchange Server 2019 Mainstream Support ended on January 9, 2024 – but has few consequences

Exchange Logo[German]Small addendum from this week. Microsoft points out in a post that mainstream support for Exchange Server 2019 ended on January 9, 2024. Before anyone panics, this has no consequences for the time being, as Exchange Server 2019 is still in (extended) support. Microsoft will also roll out two more CUs for Exchange Server 2019. Here is a brief overview of the status.


Exchange Server 2019 support end

There is a short tech community post titled Mainstream Support for Exchange Server 2019 Ends Today dated January 9, 2024, which indicates the end of mainstream support for Exchange Server 2019.

Mainstream Support for Exchange Server 2019 Ends Today

Mainstream support simply means that Exchange Server 2019 will no longer receive functional fixes via cumulative updates (CUs) for known problems and Microsoft will discontinue further development. I will explain below why this is not true in the current case.

At this point, a clarification from Microsoft that cannot be found in the tech community article above. January 9, 2024 is the last date for Microsoft until which customers could request a bug fix or a Design Change Request (DCR) for the Exchange team to consider. From now on, Microsoft's developers will only consider security fixes.

However, security updates will be provided until the end of support for Exchange Server 2019. General support for Exchange Server 2019 will then end on October 14, 2025 – so there are almost two years left until Microsoft has to make a statement regarding a successor.

Exchange Server 2019 gets two more CUs

Let's now come to the crux of the matter, which I already addressed in December 2023 in the blog post Exchange Server 2019: No more CUs in 2023; CU14 and CU15 coming in 2024. On November 21, 2023, the Exchange team announced the rollout of the planned CUs for Exchange Server 2019.


  • The cumulative update 2023 H2 (CU14) for Exchange Server 2019 was actually planned for the end of 2023. This rollout has been postponed to the first half of 2024. I had expected it on January 9, 2024, but it does not seem to have been released.
  • Microsoft is also preparing the Cumulative Update 2024 H2 (CU15) for Exchange Server 2019, which is to be rolled out in the second half of 2024.

For CU14, Microsoft promises support for TLS 1.3, a correction to S/MIME control, enhanced protection enabled by default and more (see the Techcommunity article Servicing Exchange Server 2019).

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