Proof of Purchase Coding!!!

I have an existing website that needs to have a few small features added PHP coding! 1) When a user on the site presses the button to continue to the payment process, a file with a specific name needs to be created on the server. The name of the file will be the main email address the user specifies on the page, with a .htm extension at the end. (This will go into a folder named registered that is located on our server.) The only data that would go into this file is if the user provides us with an additional e-mail. Then that would be written as text inside this file. But if they don't provide an additional e-mail. Then there doesn't need to be any data in that file. The file is really just there so that we can keep record of our clients, in other words there will be one file for each client. 2) At the same time, an email must be sent to a fixed email address that we will specify (we can hardcode this into the program ourselves…. just put a generic e-mail name in that spot). The email also must be sent "behind the scenes", without the user knowing about it. Basically it will be sent to our support department as a notification that a sale has been made. 3) This may change the order of how the first 2 steps work, but that is okay. I need help coming up with an automated system that will verify (Proof of Purchase) that the user has paid. In order for “step 1 and 2” to be fully completed, there needs to be some system in place that verifies that the person has actually bought our software. Once step 1 has been completed, and the file is created, our software is unlocked for that user. Also, we are “NOT” using PayPal, we are using “[login to view URL]” because we have an affiliate program set up through them. So please do not respond to this if you are suggesting that we use PayPal. I know PayPal has a great “Proof of Purchase” method but we are “ONLY” going to be using [login to view URL] for these purchase. So if you have used [login to view URL] to set up an (Proof of Purchase) method before, please respond! Or if you have any other idea’s that may work “along with using ClickBank” please respond and explain your idea for this process! Let me know if you have questions, thanks! -Robert Harris