title: Mailbox Unavailable in c#
body: <p>I am attempting to email myself through my program, using this method:</p>
  
  <pre><code>MailMessage email = new MailMessage("IT_REQUEST@creandsel.com.au", "ben.hall@creandsel.com.au");
  SmtpClient client = new SmtpClient();
  client.Port = 25;
  client.DeliveryMethod = SmtpDeliveryMethod.Network;
  client.UseDefaultCredentials = false;
  client.Host = "hp132.hostpapa.com";
  email.Subject = "New IT Request";
  email.Body = Model.Description;
  
  client.Send(email); // Error catches here
  </code></pre>
  
  <p>However I am getting the error message: </p>
  
  <blockquote>
    <p>Mailbox unavailable. The server response was: Access denied - Invalid HELO name (See RFC2821 4.1.1.1)</p>
  </blockquote>
  
  <p>I have tried alternate hosts (creandsel.com.au), to the same effect. I believe it may be because I am sending this from an internal network to a third party email provider.</p>
  
  <p>Also, not sure if this matters, but the sender (IT_REQUEST@creandsel.com.au) does not exist.</p>