If your organisation is still running Exchange Server 2016 or 2019 on-premises, the end-of-support deadline of October 14, 2025 has passed. Microsoft has ended security patches and technical support for both versions. Exchange Server Subscription Edition (SE), released July 2025, is the replacement, and Hamilton365 can help organisations plan and execute the upgrade.
Exchange Server SE is the latest version of on-premises Exchange, moving to a subscription licensing model. Built on Exchange Server 2019 CU15, it delivers continuous updates and security patches rather than the traditional infrequent cumulative update cycle.
No more security patches, any vulnerabilities discovered after October 14, 2025 will not be addressed. No technical support from Microsoft. Compliance exposure for regulated industries. Exchange has historically been one of the most actively exploited server products, running unpatched is a material security risk.
Exchange 2019 CU14 or CU15, in-place upgrade to Exchange SE is supported. Exchange 2016, requires a migration approach; coexistence with Exchange SE is supported until Exchange SE CU2 (second half of 2026).
Hamilton365 Exchange Migration Services