Starting October 1, 2026, EWS access will be blocked for mailboxes with Exchange Online Kiosk, Microsoft 365/Office 365 F1, and F3 licenses. To maintain EWS access, users must be assigned licenses with EWS rights, such as Exchange Online Plan 1/2 or Microsoft 365 E3/E5.
Applies to: Exchange Online
Source: mc.merill.net — data via Merill Fernando's open archive (MIT).