title: System.Net Error: 0 : [8764] Exception in the SmtpClient#39532060::Send - Unable to read data from the transport connection : net_io_connectionclosed
body: <p>I know that this question looks like duplicate of other questions while it's not.</p>
  
  <p>Whenever I try to send an email on production through my web application an SMTPException is thrown (not all the time, once per four times) and the exception is :</p>
  
  <pre><code>System.Net Error: 0 : [8764] Exception in the SmtpClient#39532060::Send - Unable to read data from the transport connection : net_io_connectionclosed.
  </code></pre>
  
  <p>While the code on local is working perfectly, the same code, the same connections, the same credentials.</p>
  
  <p>The config in both local and production :</p>
  
  <pre><code>&lt;system.net&gt;
   &lt;mailSettings&gt;
    &lt;smtp deliveryMethod="Network" from="@email"&gt;
     &lt;network host="mailtrap.io" password="@pwd" port="25" userName="@usr"/&gt;
    &lt;/smtp&gt;
   &lt;/mailSettings&gt;
  &lt;/system.net&gt;
  </code></pre>
  
  <p>Can anyone give just a hint what could be the problem that raising this issue?</p>