What you need to know
Microsoft’s lifecycle pages show Exchange Server 2016 and 2019 reached end of support on October 14, 2025, after which there are no new security updates or assisted support. Exchange Server Subscription Edition, which started July 1, 2025 under the Modern Lifecycle Policy, is listed as in support.
Potentially affected
Organizations still running on-premises Exchange Server 2016 or 2019, including servers kept for hybrid management or SMTP relay, and the providers who maintain them.
DSE recommendation
DSE recommends retiring or upgrading every Exchange Server 2016 and 2019 installation, and treating any that remain as unpatched servers until they are gone.
Microsoft’s lifecycle pages show Exchange Server 2016 and 2019 reached end of support on October 14, 2025, after which there are no new security updates or assisted support. Exchange Server Subscription Edition, which started July 1, 2025 under the Modern Lifecycle Policy, is listed as in support.
Source facts
Microsoft’s lifecycle pages for Exchange Server 2019 and Exchange Server 2016 show both follow the Fixed Lifecycle Policy, with mainstream support ending in January 2024 for 2019 and in October 2020 for 2016. Microsoft’s list of products ending support in 2025 shows both reaching end of support on October 14, 2025.
That list says that upon retirement or end of support there are no new security updates, non-security updates, free or paid assisted support options or online technical content updates. The Exchange Server 2016 page tells customers to move to the most recent cumulative update for Exchange Server 2019 to be prepared for an in-place upgrade to Exchange Server SE.
Microsoft’s Exchange Server Subscription Edition lifecycle page shows it follows the Modern Lifecycle Policy, with a start date of July 1, 2025, and lists it as in support.
Applicability
Use this for any organization with on-premises Exchange servers, including servers kept only for hybrid management or relay. Licensing for Exchange Server SE and migration paths to Exchange Online vary; confirm them with Microsoft or a licensing partner.
DSE recommendation
DSE recommends retiring or upgrading every Exchange Server 2016 and 2019 installation, and treating any that remain as unpatched servers until they are gone. Move mailboxes to Exchange Online or Exchange Server SE, bring Exchange 2019 to its latest cumulative update before an in-place upgrade, repoint scanners, alarm panels and applications that relay through Exchange, and restrict any remaining server to internal access.
Verification
Inventory Exchange servers and their versions, confirm each is retired or on Exchange Server SE, and check that no DNS records, firewall rules or connectors still point to retired servers.
Official references
Microsoft Lifecycle — Exchange Server 2019. Microsoft Lifecycle — Exchange Server 2016. Microsoft Lifecycle — Ending Support in 2025. Microsoft Lifecycle — Exchange Server Subscription Edition. Reviewed October 18, 2026.
Review the official source
Microsoft Lifecycle — Exchange Server 2019 · Verified October 18, 2026
Need help applying this guidance safely?
DSE can help confirm applicability, protect service continuity, and validate the result across physical security and IT systems.
Talk with DSE