title: set transaction_subject PayPal IPN
body: <p>Does anyone know how to set the transaction_subject in the return IPN from PayPal.</p>
  
  <p>At the moment it is returning with the same content as my custom field even though the PayPal doc's say the following:</p>
  
  <p>"Pass-through variable for your own tracking purposes, which buyers do not see.
  Default – No variable is passed back to you. "</p>
  
  <p>I need this to be different from the custom field because the transaction_subject is showing in the email that the buyer gets, which means they are seeing the contents of the custom field.</p>
  
  <p>Thanks</p>