Microsoft will discontinue the API for linking to Exchange Online and Office 365 in 2026

Microsoft warns that the Exchange Web Services API for Exchange Online and Office 365 will be phased out by the end of 2026. Developers who use the API to create software that works with Exchange and Office should use the Graph API.

Microsoft stops the api effective October 1, 2026. From that moment on, third-party apps will no longer be able to connect to Exchange Online or to Microsoft 365 via Exchange Web Services. The EWS API for Exchange Server will continue to exist. Microsoft also says the changes only apply to third-party apps, but the official Outlook and Teams apps will continue to work.

The Exchange Web Services API is a tool that allows developers to create custom software that connects to Exchange Online. These could, for example, be third-party clients for e-mail or calendars. Microsoft does not mention a specific reason for the discontinuation, but refers to its own life cycle policy for older software.

Microsoft says that in the future it will be best for developers to switch to Graph, a broader set of APIs intended for connections to Microsoft 365. EWS will continue to receive security updates until October 2026. Non-security updates are also released periodically, although Microsoft does not provide details about these. The changes also apply to the Java and .NET SDKs that work with EWS.