title: Sending invitation mail and receiving response with receiver's email address
body: <p>I am sending an invitation message through email for two person, with two link buttons (Approve/Reject) options.</p>
  
  <p>Now, How do I know who has clicked on <strong>Approve</strong> button? So I can send an extra mail for the one who clicked on <strong>Approve</strong> button.</p>
  
  <p>I am sending the mail through PHP code.</p>
  
  <p>The links somehow looks like below</p>
  
  <p>For Approve Button
  <a href="http://192.198.0.0/webApp/process.php?response=1" rel="nofollow noreferrer">http://192.198.0.0/webApp/process.php?response=1</a></p>
  
  <p>For Reject Button
  <a href="http://192.198.0.0/webApp/process.php?response=0" rel="nofollow noreferrer">http://192.198.0.0/webApp/process.php?response=0</a></p>
  
  <p>I am asking this to find a perfect idea or solution!</p>