Digital Downloads Without Registration Requirements

I have a client that has been selling physical goods for a while now and she just recently asked me to remove the requirement for the customer to register for them to be able to purchase from her website. She now wants to sell digital goods and again doesn't want the customer to have to register to be able to download their purchases. I have reviewed the "How to Create a Download Center" but obviously this will not work with her requirements as it requires users to have login accounts. I am wondering if anyone has created such a system using eCart and other WebAssist tools? I thought that an email sent to the customer after payment confirmation with some sort of encrypted link would work. Just looking for a little guidance.