Retirement of RBAC Application Impersonation in Exchange Online

Application Impersonation Role Retirement: Below are the latest recommendation from Microsoft.

EWS impersonation provides a mechanism for EWS applications that run as a service account to act as a user, whereas With Microsoft Graph there are no service accounts.

 

Instead, permissions are granted to applications directly, the way to achieve Impersonation in Microsoft Graph is by making use of app-access policy and application permissions.

 

You can learn more about this from the Microsoft Document here:  
https://learn.microsoft.com/en-us/graph/migrate-exchange-web-services-authentication#impersonation 

• consider using the Microsoft identity platform / application model for building apps that integrate with Microsoft cloud data.
• Register your app in Microsoft Azure, utilize OAuth for secure access, and follow best practices for permissions and visibility.
• If you have EWS applications requiring access to multiple mailboxes, ensure they are configured properly with OAuth for App-only access.

Exchange Web Service Mapping with MS Graph APIs: You can find the Graph API's mapping in the Microsoft article below.
Exchange Web Services (EWS) to Microsoft Graph API mappings - Microsoft Graph | Microsoft Learn