title: SendGrid SMTP error {"Unable to read data from the transport connection: net_io_connectionclosed."}
body: <p>This might seem to be duplicate but it is not. I tried restarting the IIS, enclosing the SMTPClient in the using block etc. But Still I'm getting the error. </p>
  
  <pre><code>try
  {
     //I have replaced sender@gmail.com and receiver@gmail.com by a valid gmail addresses
      MailAddress sender = new MailAddress("sender@gmail.com");
      MailAddress receiver = new MailAddress("receiver@gmail.com");
      MailMessage mailMsg = new MailMessage(sender, receiver);
      mailMsg.Subject = "subject";
  
      string text = "text body";
      string html = @"&lt;p&gt;html body&lt;/p&gt;";
  
      mailMsg.AlternateViews.Add(AlternateView.CreateAlternateViewFromString(text,  null, MediaTypeNames.Text.Plain));
      mailMsg.AlternateViews.Add(AlternateView.CreateAlternateViewFromString(html, null, MediaTypeNames.Text.Html));
  
  
      using(SmtpClient smtpClient = new SmtpClient())
          {
             smtpClient.Host = "smtp.sendgrid.net";
             smtpClient.Port = 587;
             smtpClient.EnableSsl = true;
  
            //UserName = Username of SendGrid account, Password = Password of SendGrid account
             System.Net.NetworkCredential credentials = new System.Net.NetworkCredential("UserName", "password");
             smtpClient.Credentials = credentials;
             smtpClient.ServicePoint.MaxIdleTime = 1; /* without this the connection is idle too long and not terminated, times out at the server and gives sequencing errors */
  
             smtpClient.Send(mailMsg);            
  
           }            
  }
  catch (SmtpException ex)
       {
           Console.WriteLine(ex.Message);
       }
  
  catch (Exception ex)
       {
            Console.WriteLine(ex.Message);
       }
  </code></pre>
  
  <p>This is a MVC application developed in VS 2015. </p>
  
  <p>Any input on this will be helpful.</p>