Fetching Email content with Microsoft graph API using admin credentials

Question

I am trying to retrieve the outlook messages of an user using the following API end point -

https://graph.microsoft.com/v1.0/users/{userPrincipalName}/messages

However, it is not working at all. I am the admin and hence using my own credentials (instead of using an app)
It works fine if I want to see my own data with this call - https://graph.microsoft.com/v1.0/users/me/messages

Answer 1

You need to do the following:

• Some apps call Microsoft Graph with their own identity and not on behalf of a user (say, Client Credential flow). For this you need to start with setting authentication/authorization steps as described here[https://learn.microsoft.com/en-us/graph/auth-v2-service#authentication-and-authorization-steps] and the detailed steps.
• Configure the permissions for Microsoft Graph
• Get admin consent, get access token and use it to call Graph
• Now you can access the other user mailbox and its items.