Exchange Server 2016 and the End of Mainstream Support

As hopefully many of you already know Exchange Server 2016 enters the Extended Support phase of its product lifecycle on October 14th 2020. That’s just a few short months away.

During Extended Support, products receive only updates defined as Critical consistent with the Security Update Guide. For Exchange Server 2016, critical updates will also include any required product updates due to time zone definition changes. With the transition of Exchange Server 2016 to Extended Support, the quarterly release schedule of cumulative updates (CU) will end. The last planned CU for Exchange Server 2016, CU19, will be released in December 2020.   

There is one more consideration for this change that we want to address here today, and that is the ongoing use of Exchange Server 2016 for recipient management for hybrid organizations that have moved all their mailboxes to the cloud.

As you probably also know we have historically provided a free license for these ‘management’ servers if their only use is to properly manage Exchange attributes when recipient objects are mastered on-premises. You also know that we never provided this free license type for Exchange Server 2019.

We want to assure you that we are still committed to delivering a solution that will allow these lingering servers to be removed, but it will not arrive before Exchange Server 2016 enters Extended Support.

For this reason, we want to make our recommendation for this scenario clear. Our broad recommendation is to keep Exchange Server 2016 in production use until such point as we release a solution that allows those servers to be removed. As explained earlier, Extended Support still provides security and time zone updates and so keeping them in production and ensuring they are properly patched does not increase your risk profile in any way.

If you can’t move your mailboxes to the cloud and you plan on keeping mailboxes on-premises, then you really should be moving to Exchange Server 2019, and using that for both mailboxes and hybrid connectivity. That way you get full support including non-critical bug fixes and get ongoing product improvements.

When we have a solution available to allow any management-only servers to be removed, it may require an update to Exchange Server 2016, and in that case we may release a future CU or patch. Currently there is no plan to release future updates for Exchange 2016, but we want to assure our customers that if we need to do this to support the removal of these ‘management only’ servers, we will.  

Microsoft encourages Exchange Server 2016 customers to adopt CU19 as soon as possible to ensure uninterrupted delivery of any future security related fixes. After December 15, 2020, only CU19 or its successors will receive critical updates. During the Extended Support phase, only the latest CU is eligible to receive critical updates once the standard 3 month transition period of the prior CU has lapsed.  

Critical updates will continue to be made available via Windows Update and the Microsoft Download Center. Additional lifecycle information for all Microsoft products is available on

We hope this update was informative and we look forward to hearing your feedback and answering any questions you may still have.

The Exchange Team

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