Exchange Web Services enters the final stretch before Microsoft pulls access

Microsoft Exchange Web Services (EWS) in Exchange Online is set for permanent retirement on April 1, 2027. Introduced with Exchange Server 2007, EWS enables applications to access mailbox data such as email, calendars, and contacts. Microsoft cites security, scalability, and reliability reasons for discontinuing the service and urges integrations to migrate to Microsoft Graph.

Starting October 1, Microsoft will adjust tenant-level EwsEnabled settings left at $null to $false, effectively blocking EWS. Administrators can temporarily maintain continuity by explicitly setting the value to $true and adding approved applications to the EwsAllowedAppIDs list. However, those unlisted applications will be blocked.

Microsoft has made it clear: "There will be no exceptions." EWS in on-premises Exchange Server will not be affected by this retirement. While Microsoft has provided ample time for preparation, the migration process is not without challenges. Identifying every EWS dependency is a significant hurdle due to rapid integration rollouts and limited documentation.

Translation layers that convert EWS calls to Microsoft Graph requests can serve as a temporary workaround but do not eliminate the need for a full migration. Instead of waiting for deprecation notices, organizations should continuously monitor APIs as dependencies throughout their lifecycle, according to Markus Müller, global field CTO for API management at Boomi.

The extent of remaining EWS usage by organizations or processes is unknown. Any overlooked integrations will surface as tenants are phased out of EWS, likely through support tickets reporting that previously functional workflows have unexpectedly ceased.