title: C# Mailkit delivery status notification
body: <p>I am creating an email management system using MailKit.</p>
  
  <p>I need to track delivery but all I can find is the <code>DeliveryStatusNotification enum</code>, but nowhere to apply it.</p>
  
  <p>What I have so far is:</p>
  
  <pre><code>var message = new MimeMessage();
  DeliveryStatusNotification delivery = 
    DeliveryStatusNotification.Delay |
    DeliveryStatusNotification.Failure |
    DeliveryStatusNotification.Never |
    DeliveryStatusNotification.Success;
  message.Headers.Add(new Header(HeaderId.ReturnReceiptTo, "test@example.com")); // Delivery report
  </code></pre>
  
  <p>Guide me in the right direction??</p>