401未經授權而訂閱與Exchange服務和OAuth

Question

我試圖訪問EWS託管API推送通知（訂閱推送通知），通過OAuth如下：

var authenticationTask = await authenticationContext.AcquireTokenAsync("https://outlook.office365.com", new ClientCredential(clientID, clientSecret)); 
string targetSmtp = "user123@mydomain.onmicrosoft.com"; 
ExchangeService exchangeService = new ExchangeService(ExchangeVersion.Exchange2013); 
exchangeService.Url = someURL; 
exchangeService.TraceEnabled = true; 
exchangeService.TraceFlags = TraceFlags.All; 
exchangeService.ImpersonatedUserId = new ImpersonatedUserId(ConnectingIdType.PrincipalName, "user123@mydomain.onmicrosoft.com"); 
exchangeService.HttpHeaders.Add("X-AnchorMailbox", targetSmtp); 
exchangeService.Credentials = new OAuthCredentials(authenticationTask.AccessToken); 
PushSubscription subscription = exchangeService.SubscribeToPushNotifications(
              new[] { someFolder }, 
              new Uri(postBackUrl), 
              15, 
              null, 
              EventType.NewMail, 
              EventType.Created, 
              EventType.Deleted, 
              EventType.Modified, 
              EventType.Moved, 
              EventType.Copied); 

我能夠得到令牌我應用程序，但同時認購推送通知用戶（user123@mydomain.onmicrosoft.com）我得到"The request failed. The remote server returned an error: (401) Unauthorized."錯誤

更新：嘗試以下這裏所說的完全一樣的步驟：Azure AD app-only access tokens for exchange impersonation但仍然得到401

Answer 1

對於那些在同一個問題上掙扎的人，我們需要通過使用證書（而不是使用客戶機密鑰）來獲取已註冊應用程序的訪問令牌。有關如何操作的更多詳細信息，請參閱：https://blogs.msdn.microsoft.com/exchangedev/2015/01/21/building-daemon-or-service-apps-with-office-365-mail-calendar-and-contacts-apis-oauth2-client-credential-flow/