Microsoft has officially alerted system administrators that Exchange Server 2016 and Exchange Server 2019 are set to reach the end of their extended support phase this October. The implications for businesses still relying on these older server versions could be significant.

Exchange 2016 already ended its mainstream support in October 2020, and while Exchange 2019 is still operational, its mainstream support will wrap up on January 9, 2024. As the clock ticks down, Microsoft is urging users to prepare for the inevitable transition away from these outdated systems.

Mark your calendars! On October 14, 2025—just nine months from now—both Exchange Server 2016 and Exchange Server 2019 will officially hit the end of support milestone. Although existing installations will continue to function, Microsoft warns that without support, users may expose themselves to security risks and technical challenges.

Once the end-of-support date arrives, Microsoft will no longer offer technical assistance for Exchange 2016 or 2019, which includes crucial bug fixes and security patches. This creates a potential vulnerability for organizations that do not upgrade, as they will be at increased risk for security breaches and other significant technical failures.

Time to Upgrade or Migrate!

To avoid these pitfalls, Microsoft strongly recommends that administrators consider migrating to Exchange Online—available either as part of an Office 365 subscription or as a standalone service—or prepare to upgrade to the forthcoming Exchange Server Subscription Edition (SE), which is set to launch in the early part of the second half of 2025.

For those looking to upgrade, an in-place upgrade from Exchange Server 2019 to Exchange Server SE will be straightforward, resembling the familiar process of installing a Cumulative Update (CU). This streamlined upgrade path ensures that businesses can transition seamlessly while gaining access to more robust features and improved support.

The Exchange Team notes, “To facilitate these upgrades, we have either introduced new features in Exchange Server 2019 CU15 or reserved them for Exchange Server SE CU1 and beyond. Thus, while Exchange SE will be branded as an update, it actually represents a significant shift in support policies and lifecycle.”

Switching to Exchange Server SE RTM positions your organization on a supported trajectory, ensuring compatibility with future updates. Once Exchange SE CU1 is live, users of older versions will find themselves unsupported, adding urgency to the upgrade timeline.

In this era where cyber threats continue to evolve, maintaining the security and reliability of your email infrastructure is crucial. Don't wait until it's too late—act now to safeguard your organization’s technological foundation!