Exchange Web Services (EWS) in Exchange Online will retire starting October 1, 2026, with full retirement by April 1, 2027. Microsoft introduced EWSAllowedAppIDs, allowing admins to create an allow list of approved apps to manage EWS access and reduce disruption. Immediate preparation is recommended.
Applies to: Exchange Online
Source: mc.merill.net — data via Merill Fernando's open archive (MIT).