Microsoft Message ID

Summary

• Microsoft has announced the final retirement timeline for Exchange Web Services (EWS) in Exchange Online, transitioning all functionality to Microsoft Graph.
• The retirement follows a phased approach: a “soft” disablement phase begins October 1, 2026, followed by a permanent shutdown on April 1, 2027.
• This change is driven by the need for improved security, modern authentication standards, and the broader integration capabilities offered by the Microsoft Graph API.
• Note: This retirement only applies to Exchange Online; Exchange Server (on-premises) is not affected by this specific update.

Impact

• Application Failure: Any custom-built or third-party vendor applications currently using EWS to access mail, calendar, or contact data will stop functioning if not migrated to Microsoft Graph.
• October 2026 Deadline: Microsoft will set EWSEnabled to False by default. EWS traffic will be blocked unless an administrator has explicitly configured an AppID AllowList.
• April 2027 Deadline: EWS will be fully decommissioned. After this date, no administrative overrides will be possible, and all EWS-based integrations will permanently fail.
• Scream Tests: Microsoft may perform temporary service interruptions (“scream tests”) prior to October 2026 to help organizations identify forgotten or undocumented EWS dependencies.
• Administrative Overhead: Admins will need to manage AllowLists for any legacy applications that cannot be migrated before the initial October 2026 milestone.

Action Required

• Inventory EWS Usage: Use the Microsoft 365 admin center reports or specialized PowerShell scripts to identify which applications and service accounts are currently making EWS calls.
• Migration Planning: Begin transitioning EWS-based workflows to Microsoft Graph. Microsoft Graph now offers near-complete parity for the features most commonly used in EWS.
• Configure AllowLists: If certain applications cannot be migrated before October 2026, ensure you configure the “AppID AllowList” and set EWSEnabled=True via tenant settings before the end of August 2026.
• Vendor Engagement: Contact third-party software vendors (e.g., backup, CRM, or ticketing systems) to ensure their products support Microsoft Graph and to obtain necessary update schedules.
• Documentation: Update internal technical documentation to reflect the move away from legacy EWS endpoints and the adoption of Graph API permissions.