Hi Dave,
Thanks for the detailed answer.
One problem you have with DNN6 is that it injects the full page content for the autoresponse, so you have to use a Notify Provider to pickup the autoresponse.
Sorry, I am using DNN6 but didn't follow this sentence at all! What is the Notify Provider you refer to? Using PayPal for example, is that the IPN (Instant Payment Notification) feature?
Thanks