MC1191578: Update to EWS Access for Kiosk / Frontline Worker Licenses
Starting March 1, 2026, EWS access will be blocked for mailboxes with Exchange Online Kiosk, Microsoft 365/Office 365 F1, and F3 licenses, which currently lack EWS rights. To maintain EWS access, users must be assigned licenses with EWS rights, or EWS requests will return HTTP 403 errors.