Microsoft Replaces Exchange Web Services with Cross-Tenant Access Policy in Microsoft 365
Microsoft is phasing out Exchange Web Services (EWS) and replacing it with Cross-Tenant Access Policy (CTAP), a more modern, secure framework for cross-tenant collaboration in Microsoft 365.
The transition affects Free/Busy sharing, MailTips, and calendar sharing between organizations. CTAP will become the new standard for these features, replacing older Exchange Online mechanisms such as organization relationships, availability address spaces, and sharing policies.
Microsoft recommends testing and migrating to CTAP before EWS retirement to ensure uninterrupted collaboration capabilities. Organizations that share calendar and availability data with external Microsoft 365 tenants should review their current configurations and plan a migration to CTAP for secure and modern cross-tenant collaboration.