GRAPH API - get user mailbox forbidden access error

Question

Hello, I would like to get and then set shared mailbox settings. I would like to get mailbox settings first, but I can't overcome the forbidden access problem. https://graph.microsoft.com/v1.0/users/Room@MyTenant.onmicrosoft.com/messages I am using the request from above. I granted permissions in Modify Permissions tab. Should I provide some Request headers or anything else to make it work? Error:

{
    "error": {
        "code": "ErrorAccessDenied",
        "message": "Access is denied. Check credentials and try again."
    }
}

Answer 1

You cannot use the Delegate permissions model to access or configure other user's settings. Use Application permissions instead.