Microsoft confirmed Exchange Web Services will stop working in Exchange Online on April 1, 2027. The API, first released with Exchange Server 2007, faces mandatory retirement after nearly two decades of operation.
Organizations using Microsoft 365 must complete migrations to Microsoft Graph before the final deadline. Microsoft established a phased timeline starting October 1, 2026, when EWS becomes blocked by default.
Administrators can maintain temporary access through application allow lists configured by the end of August 2026.
The company cited security vulnerabilities and outdated architecture as primary reasons for the shutdown.
"EWS was built nearly 20 years ago, and while it served the ecosystem well, it no longer matches today's security, scale, or reliability requirements,"
Microsoft's Exchange Team stated. The
Microsoft Graph now offers near-complete feature parity for most EWS scenarios, according to company documentation. Many third-party applications have already started migrating to the newer API.
Microsoft acknowledged it has not finished moving all its own affected applications to Graph.
The retirement affects only cloud-based Exchange Online and Microsoft 365 environments. On-premises Exchange Server installations continue supporting EWS without changes. Hybrid configurations require Exchange Server Subscription Edition for Graph connectivity to cloud mailboxes.
Microsoft plans temporary "scream tests" where EWS gets disabled briefly to identify hidden dependencies. Administrators will receive monthly usage reports through Message Center notifications.
The company urged immediate review of EWS usage data available in Microsoft 365 admin portals.
Applications still dependent on EWS will cease functioning in cloud mailboxes after April 2027. Microsoft confirmed no exceptions will be granted past the final shutdown date.
The company promised additional guidance in coming weeks as organizations prepare for the transition. This follows other recent Microsoft service retirements like the 3D Viewer app removal scheduled for July 2026.
