For every customer using the cloud solutions of Exchange Online in combination with a Microsoft 365 subscription it is highly recommended to change to Graph API by November 2022. The Phishing Report Button will no longer be able to render any email information with the REST API. Alternatively, depending on your set up, customers can still fallback to EWS API if needed. However, this is not recommended as this will restrict the Phishing Report Button feature set. Please, check our updated Outlook client and server API compatibility matrix here to ensure you choose the proper API according to your set up.
Exchange On-Premises hybrid deployments
Customers using a hybrid configuration (Microsoft 365 + Exchange On-Premises) are able to use REST API until March 2023. After that, all REST API requests will be blocked by Microsoft, and we ask you to contact Microsoft for further steps on migration.
Please find our updated Outlook client and server API compatibility here.
From Microsoft | Using the Outlook REST API (version 2.0): Use REST APIs to access mailboxes in Exchange hybrid deployments (deprecated) - Microsoft Graph
Recommended: We strongly recommend customers to contact Microsoft support to correctly proceed and migrate according to their setup.