title: How to track the email whether has been opened by end user
body: <p>I got a especial requirement is track the email whether has been opened by end user.</p>
  
  <p>Logic is :</p>
  
  <ol>
  <li>asp.net program got user email address list from database</li>
  <li>send email notification to users based on that address list</li>
  <li>when user open the email, the sender(web site server) will get a request or update to mark the record has been read in database</li>
  </ol>
  
  <p>I don't owns the mail server, so maybe use hotmail\gmail to send email notification.</p>
  
  <p>Based on my description, anyone can help me out? Or let me know if this can be implemented?
  Many thanks and kindly show me your ideas!</p>