401订阅使用Exchange服务和OAuth的推送通知时未经授权

Question

我正在尝试使用oauth访问EWS托管API（订阅推送通知），如下所示：

var authenticationTask = await authenticationContext.AcquireTokenAsync("https://outlook.office365.com", new ClientCredential(clientID, clientSecret));
string targetSmtp = "[email protected]";
ExchangeService exchangeService = new ExchangeService(ExchangeVersion.Exchange2013);
exchangeService.Url = someURL;
exchangeService.TraceEnabled = true;
exchangeService.TraceFlags = TraceFlags.All;
exchangeService.ImpersonatedUserId = new ImpersonatedUserId(ConnectingIdType.PrincipalName, "[email protected]");
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);

我能够获得我的应用程序的令牌，但在订阅用户（[email protected]）进行推送通知时，我得到"The request failed. The remote server returned an error: (401) Unauthorized."错误

更新：尝试按照此处提到的完全相同的步骤：Azure AD app-only access tokens for exchange impersonation但仍然获得401。

Ashish

Answer 1

对于那些在同一问题上苦苦挣扎的人，我们需要使用证书（而不是使用客户端密钥）来获取已注册应用程序的访问令牌。有关如何操作的更多详细信息，请参阅：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/