title: Getting referer info from Paypal successful payment?
body: <p>Let's say someone paid successfully and redirected to my "successful payment" page. Can I track the referer url by</p>
  
  <pre><code>$_SERVER['HTTP_REFERER'];
  </code></pre>
  
  <p>I want to do this because I should show "thank you" page only if visitor comes from paypal.</p>