C# Office 365模拟

我试图在模拟User2时从我的Office 365帐户发送电子邮件

        {
            ExchangeService service = new ExchangeService();

            string fromUserEmail = new string("User2@domain");
                       
            service.Credentials = new WebCredentials("User1@domain", "password");
            service.UseDefaultCredentials = false;
            service.ImpersonatedUserId = new ImpersonatedUserId(ConnectingIdType.SmtpAddress, fromUserEmail);
            service.Url = new Uri("https://outlook.office365.com/EWS/Exchange.asmx");

            EmailMessage email = new EmailMessage(service);

            email.ToRecipients.Add("someone@somewhere");
            email.ReplyTo.Add(replyToEmail);
            email.Subject = "HelloWorld";
            email.Body = new MessageBody("Test message");

            email.Send();
        }

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我在email.Send（）上收到System.NullReferenceException:“对象引用未设置为对象的实例。”。当我注释掉这个服务时，模仿就可以了。我做错了什么？

解决了。我需要你的许可

New-ManagementRoleAssignment -Name:User1_impersonation -Role:ApplicationImpersonation -User: "User1@domain"

我不知道为什么VisualStudio没有提供更有用的错误消息