title: smtp email send request fails sometimes
body: <p>I am using below code in c#,</p>
  
  <pre><code>string Subject = "test12";     
      MailMessage mail = new MailMessage();
      mail.To.Add(item.ToString());
      mail.From = new MailAddress(EmailUserName);
      mail.Subject = Subject;
      mail.Body = PopulateBody();       
      mail.IsBodyHtml = true;
      SmtpClient client = new SmtpClient(EmailHost, EmailPort);        
      client.EnableSsl = true;
      NetworkCredential credentials = new NetworkCredential(EmailUserName, EmailPassword);
  
      client.UseDefaultCredentials = false;
      client.Credentials = credentials;
      client.Send(mail);
  </code></pre>
  
  <p>I am getting error in Client.send(mail) method</p>
  
  <p>What I have tried:</p>
  
  <p>System.Security.Authentication.AuthenticationException: A call to SSPI failed, see inner exception. ---> System.ComponentModel.Win32Exception: The function requested is not supported
  --- End of inner exception stack trace ---
  at System.Net.Security.SslState.StartSendAuthResetSignal(ProtocolToken message, AsyncProtocolRequest asyncRequest, Exception exception)
  at </p>