无法使用Gmail的应用程序密码从C＃Win表单应用发送电子邮件

Question

我们曾经发送带有不太安全的应用程序选项的电子邮件，这是不再可能的。我已经设置了两种身份验证，我创建了一个应用程序密码，但是当我尝试发送带有应用程序密码的电子邮件而不是帐户密码时，我会收到错误：

System.Net.Mail.SmtpException: Failure sending mail.
 ---> System.IO.IOException: Unable to read data from the transport connection: The connection was closed.

发送的代码为：

Smtp = new SmtpClient();
Smtp.UseDefaultCredentials = false;
var NetworkCredentials = new NetworkCredential() { UserName = "[email protected]", Password = "..." };
Smtp.Port = 587;
Smtp.EnableSsl = true;
Smtp.Host = "smtp.gmail.com";
Smtp.Credentials = NetworkCredentials;
    
MailMessage msg = new MailMessage();
msg.From = new MailAddress("[email protected]");
msg.To.Add("[email protected]");
msg.Subject = "test";
Smtp.Send(msg);