title: PayPal PDT. Transaction id is missing in return URL
body: <p>I stumble upon very peculiar behaviour of PayPal. When I test paypal integration against paypal sandbox using localhost in URLs I'm getting transaction id back, but when I substitute localhost with actual site name transaction variables are not present. In both cases PayPal returns to my site, but when I'm not using localhost it does not return transaction info, which rendering efforts of our testers futile.</p>
  
  <p>Example:</p>
  
  <pre><code>http://localhost/paymentinfo.aspx?Product=DC - working
  http://test1/paymentinfo.aspx?Product=DC     - is not working
  </code></pre>
  
  <p>Just to be clear:</p>
  
  <ol>
  <li>PDT on my sandbox account is activated.</li>
  <li>IPN on my sandbox account is activated.</li>
  </ol>
  
  <p>Here is code of my BuyNow PayPal button:</p>
  
  <pre><code>&lt;form action="https://www.sandbox.paypal.com/cgi-bin/webscr" method="post"&gt;
  &lt;input type="hidden" name="cmd" value="_s-xclick"/&gt;
  &lt;input type="hidden" name="encrypted" value="-----BEGIN PKCS7-----DFGHJ8yuFFTY-----END PKCS7-----"/&gt;
  &lt;input type="hidden" name="bn" value="PP-BuyNowBF:btn_buynowCC_LG.gif:NonHosted"/&gt;
  &lt;input type="image" src="https://www.paypalobjects.com/en_US/i/btn/btn_buynowCC_LG.gif" border="0" name="submit" alt="PayPal - The safer, easier way to pay online!"&gt;
  &lt;img alt="" border="0" src="https://www.paypalobjects.com/en_US/i/scr/pixel.gif" width="1" height="1"&gt;
  &lt;/form&gt;
  </code></pre>
  
  <p>where ="encrypted" contains encripted string of the following list of parameters:</p>
  
  <pre><code>cmd=_xclick
  business=paypal_business_acc@companyname.com
  cert_id=123456
  charset=UTF-8
  item_name=product name
  item_number=123456
  amount=11.97
  currency_code=USD
  return=http://localhost/Success.aspx
  cancel_return=http://localhost/AppDownPay.aspx?Cancel=true
  notify_url=http://ipnlstnr/PayPalIPNListenerInternal.ashx
  custom=2bcad9cb-9429-4e99-8984-5d0532bfb718
  no_shipping=1
  on0=CustomItem1
  on1=CustomItem2
  os0=VM
  os1=DC
  </code></pre>
  
  <p>Does anyone have any idea how to make PayPal return trancation variables to the non-localhost-containg URLs?</p>
  
  <p>UPdate:
  It appeared, that PayPal sandbox has been sending messages to the IPN listener, instead of returning to our site. That's quite unexpected. Because Auto Return is on. I've tried to enable or disable PDT, which did not make any difference. Also I've tried to remove notify_url from button code and still message has been redirected to the our IPN listener and not to our site. I've tried to add "rm" variable to the button code with value of 2 and that did not convince sandbox to redirect to our site. Could you, please, help me to understand what am I missing?</p>
  
  <p>UPDATE2:
  Issue has been resolved. Problem was caused by inability of the PayPal to return to our app due to firewall restrictions. As soon, as those restrictions have been removed app started to behave normally.</p>