What is happening? Microsoft is retiring Exchange Web Services (EWS) in Microsoft 365 and Exchange Online. EWS is an older technology used by some email clients, applications, and automated processes to access mailbox data. Microsoft is directing customers to migrate to Microsoft Graph, which is the supported replacement platform.
What is changing? Microsoft has confirmed that EWS retirement will occur in phases:
- Beginning October 1, 2026, Microsoft will start disabling EWS for organizations that have not taken action to manage EWS access.
- On April 1, 2027, EWS will be permanently disabled in Exchange Online and will no longer be available. Microsoft has stated that no extensions or exceptions will be granted beyond this date.
What has IST done? To minimize disruption and allow time for application owners to transition, IST has proactively configured the University of Waterloo Microsoft 365 environment to continue supporting the current EWS applications during Microsoft's transition period. As a result, clients currently using EWS will not be impacted by Microsoft's initial changes in October.
What is the impact? If you use a third-party email application, automated process, or business application that connects to Exchange Online using EWS, that solution must eventually be updated, replaced, or migrated to Microsoft Graph before April 1, 2027. Examples may include:
- Third-party email clients
- Departmental applications
- Automated mailbox processing tools
- Vendor applications that interact with Exchange Online
What happens next? Between October 2026 and April 2027, IST will review EWS usage and directly contact individuals whose services continue to rely on EWS. Those contacted will be asked to:
- Upgrade to a version of their application that supports Microsoft Graph, or
- Work with their vendor or developer to migrate the application away from EWS and onto Microsoft Graph.
The goal is to ensure all affected services are updated before Microsoft's final EWS shutdown on April 1, 2027.
Questions or support requests? Please submit via the IST Help Portal.