Microsoft is getting serious about the impending end of extended support for Exchange 2016 and has published a guide on stripping the product from an environment that already has Exchange 2019 installed.

According to Microsoft, customers planning on sticking with on-premises Exchange for their email needs should make the jump to Exchange 2019 as soon as possible. While the next version of Exchange – Exchange SE – is due to arrive in 2025, it won’t be possible to perform an in-place upgrade to SE from 2016. Hence the need to move to Exchange 2019, even though its end-of-support date is identical to 2016.

Microsoft’s guide is a quite a bit more involved than simply shutting down the server and throwing it into landfill. For one, Exchange 2016 mailboxes must be moved to a newer version of Exchange Server and mailbox databases removed.

Microsoft also sensibly recommends popping the old Exchange 2016 servers into maintenance mode for a while, just in case anything got missed during decommissioning.

However, the era of Exchange 2016 is coming to an end. While Exchange SE – Subscription Edition – will be identical to the final Cumulative Update (CU) of Exchange 2019 except for wording in the license agreement and version number, moving from Exchange 2016 won’t be as straightforward.

Earlier this year, Microsoft gave administrators who were anxious for news about the next version of Exchange server a notification that the product would show up “early in the third quarter of calendar year 2025.” This is, assuming the company meets its deadlines, just before Exchange Server 2019 and 2016 are due to be end-of-lifed.

At the time, analysts and users alike worried that Microsoft was not providing much time for upgrades. While Scott Schnoll, Microsoft Product Marketing Manager for Exchange Online and Exchange Server, said, “A legacy upgrade from Exchange 2016 to Exchange Server SE is possible and supported,” the company recommended a move to Exchange 2019.

This advice was repeated in the guide to decommissioning Exchange Server 2016.

“If you plan to stay on-premises, we recommend moving to Exchange 2019 as soon as possible. Only Exchange 2019 will support in-place upgrades to Exchange SE, marking the first time in many years that you can perform an in-place upgrade on any Exchange release.

“You should start decommissioning Exchange 2016 servers in favor of Exchange 2019 now, to be ready for easy in-place upgrades to Exchange SE when it becomes available,” Microsoft added.

The next version of Exchange was expected in 2021 but was later delayed after several high-profile security incidents. Microsoft’s attitude to email security has come under scrutiny in recent years, and the company was recently called a threat to national security by former senior White House cyber policy director AJ Grotto.