Microsoft Exchange 2016 mainstream support ended in October 2020. What next for everyone who uses Exchange 2016 for Hybrid purposes ?
The final CU for Exchange 2016, CU19 will be released in December 2020. This means the only updates will be critical security updates, and Timezone updates. Many organisations use Exchange 2016 for recipient management tasks for their hybrid setups. Exchange 2019 has not really been used as an option here, as there is no free option for running Exchange 2019 as a hybrid.
Microsoft current recommendation is to continue to use Exchange 2016 for recipient management purposes, until a solution is released which allows these servers to be removed. Microsoft’s extended support provision will continue to allow the products to be properly patched and the risk profile not increased.
Anyone who needs to maintain mailboxes on premises should transition to Exchange 2019 as soon as possible. There is a mechanism in place to be able to migrate easily to the next version of Exchange once on 2019 too. See my blog on the subject here
Hopefully the mechanism to be able to manage recipients will soon not have a requirement for Exchange servers on premises especially if everything else has been moved to Exchange Online.