Exchange Server 2016 and 2019 reached end of support on October 14, 2025

Exchange Server 2016 and 2019 reached end of support on October 14, 2025. Migrate to Exchange Server SE or Exchange Online.

CriticalEnd of supportAction requiredIn effectVerified

Product

Exchange Server

Announced

14 October 2024

Effective from

14 October 2025

Who is affected

Organizations running on-premises Exchange Server 2016 or 2019, including hybrid deployments. Exchange Online is not affected.

Admin roles to involve: Exchange admin, Infrastructure admin, Security admin

What administrators should do

Migrate on-premises Exchange Server 2016 / 2019 to Exchange Server Subscription Edition (SE) — an in-place upgrade from 2019 — or move mailboxes to Exchange Online. After October 14, 2025 there are no security fixes, bug fixes, or support. If you keep Microsoft Entra Connect managing on-premises identities, retain at least one Exchange management server.

What happens if this is ignored

Servers keep running but receive no security updates, leaving mail infrastructure exposed to unpatched, often internet-facing vulnerabilities.

Why this is rated critical: severity comes from a fixed rubric — this entry is a end of support that requires administrator action. Time-to-deadline is shown separately and never changes the rating.

Official source

End of Support for Exchange Server 2016 and Exchange Server 2019: T-12 Months

Published by Microsoft · Source dated 14 October 2024 · Checked 24 August 2026

Last verified 24 August 2026

Related changes

Exchange Web Services (EWS) starts being disabled in Exchange Online (1 October 2026)
Office 2016 and Office 2019 reached end of support on October 14, 2025 (14 October 2025)
Skype for Business Server 2015 and 2019 reached end of support on October 14, 2025 (14 October 2025)

Keep planning

Back to the full change calendar All Microsoft 365 changes Track your own vendors and renewals