PayPal offers a system called IPN (Instant Payment Notification) and you can use this system to handle a lot of the back-end processes for your sales sites. (I'm sure that you might be saying "Great, I don't know a thing about programming PHP scripts and I don't have a clue how to set up IPN" -- that's okay because you don't have to know a thing about it). "EZY PayPal IPN Protection Generator" Is a Point And Click program that frees up your time and enhances your Internet Marketing and profitability! What does a program like this cost? That's pretty difficult to calculate but, I do know that it will save you enormous amounts of time on every product that you prepare for market, automatically deliver purchases to your customers and ensure that only people who have paid, get access to the products. | 
