title: Random "IPN was not sent, and the handshake was not verified. Review your information."
body: <p>I'm working on Paypal integration with IPN. To make it easy, I'm using the IPN Simulator. It worked few times, and now it never work again. I've tried some other DNS, and it work (sometimes). The returned message is something, well... mysterious !</p>
  
  <p><strong>IPN was not sent, and the handshake was not verified. Review your information.</strong></p>
  
  <p>I've searching the doc, and there is nothing about this message : no explanation, no advice, nothing... Information seems to be ok, and agin, it worked few times and now, it never work again : why ? How is it possible ? Is the paypal service blocked somewhere ?</p>
  
  <p>My DNS : "lecomite.eu"</p>
  
  <p>The right calling URL is "lecomite.eu/services/paypal/". All other goes to 500.</p>
  
  <p><strong>EDIT :</strong></p>
  
  <p>Ok, this is an error I've made. I apologize. But please, Paypal team, produce message a lot more informative about what's append. It should be more helpful than this undocumented <strong>IPN was not sent, and the handshake was not verified. Review your information.</strong> that don't tell anything about the transactions made, not made, send, not send, and where is the bad thing.</p>
  
  <p>NOTE : I've read your "job opportunity in the HTTP response frame" - i'm developing my own high performance web server, so I've read it.</p>