title: Acquire token for Graph API using MSAL?
body: <p>I'm attempting to use MSAL (1.0.304142221-alpha) to acquire a token for the Microsoft Graph API, using the client credentials flow. My code looks like so:</p>
  
  <pre><code>var confidentialClientApp = new ConfidentialClientApplication(clientId, redirectUri, new ClientCredential(clientSecret), null);
  var token = confidentialClientApp.AcquireTokenForClient(new string[] { "Mail.Read" }, string.Empty).Result;
  </code></pre>
  
  <p>The 2nd line throws an exception: "AADSTS70011: The provided value for the input parameter 'scope' is not valid. The scope Mail.Read is not valid.".
  The <a href="http://graph.microsoft.io/en-us/docs/api-reference/v1.0/api/message_get" rel="noreferrer">Graph API reference</a> appears to cite "Mail.Read" as the required scope.</p>
  
  <p>The application in Azure AD is a Web Application with a single key. The application has the "Read mail in all mailboxes" application permission set for Microsoft Graph.</p>
  
  <p>Could anyone shed any light as to what is going on? Thankyou :)</p>