How to allow my (desktop/server) app access to other, non-admin, users' contacts & emails

Question

I'm the admin of Office365 organization.

I've written an app that can read information from emails, and read/write contacts.

However this program doesn't have access to other users besides the admin.

I applied various permissions: application permissions, delegation permissions but there's still no access to contacts or emails of other users.

This SO guy claims to solve the problem. Yet, I can't figure out where or how to "change access token grant flow type":

"Changing OAuth 2.0 access token grant flow type from Authorization Code to Client Credentials and specifying a scope of graph.microsoft.com/.default uses the Application Type permissions"

• My app is meant to be run from my desktop, or from a server.
• The app don't have a user interface, and does NOT interact with users.
• These are the permissions I have right now:

Answer 1

Hi @Admin 6 · Thank you for reaching out.

I can confirm that it works with Client_Credentials flow with Application Permissions Contacts.Read or Contacts.ReadWrite and scope set to https://graph.microsoft.com/.default.

The problem I see in your case is, you have not granted admin consent for Contacts.Read or Contacts.ReadWrite Application permission. Delegated permissions won't work when you acquire token using client_credentials flow as it uses application context.

Please grant admin consent to these permissions and acquire a new token. Decode the new token at https://jwt.ms and make sure the roles claim include Contacts.Read or Contacts.ReadWrite or both permissions as shown below:

Once the token is acquired with above permissions, make below call along with Authorization Header with value bearer <your_access_token>:

https://graph.microsoft.com/v1.0/users/<object_id_or_upn_of_user>/contacts

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