You would want to get the information through IPN or use PDT. IPN would allow for you to receive the information and send the email regardless of if they returned or not. PDT would still require that the user returns. I only use PDT if a user is going to return and view a dynamic page such as an invoice receipt or something like that. Otherwise I use IPN, PayPal's IPN is much more reliable than hoping a user clicks a button no matter what you put in that button. By default it says "Return to Merchant" you can change that text using the 'cbt' variable in the post:



that would make the button say "Click here to complete your order" but they still might not click it.

All in all IPN would be the way to go.

If you have questions let me know.

If you set up the "Auto Return" in your PayPal account the buyer will be directed there automatically, IF they pay with a PayPal account. If they pay via Credit Card they will have to click the "Return to Merchant" link on the page. That is because there is information on the payment on that page and the buyer needs to be able to gather that Receipt number if they need it, and the Buyer paying by credit card can not login to their PayPal account to see the details because they don't have one, they are paying directly by credit card. So, you would want to collect the information to update your cart/database/website by using IPN. IPN is not dependent on a user action of clicking a link where the "Return method" or "rm" type is.

Use IPN it will save you many headaches in the future. What are you trying to do with the data when you get it?