I have a site where the user signs-up, there account is created but inactive until they click the paypal button and make a payment. The only problem is that with Paypal Standard, how can I verify that they have paid?? I have it setup so they if they click "return to site" after the payment they then go to an activation page that uses a cookie set on the join now page; however, most people click out of paypal with out going back to the site... any way to do something different? any way to auto redirect back to the site? Thanks!
For that, you need to look at the Paypal IPN https://www.paypal.com/us/cgi-bin/webscr?cmd=p/xcl/rec/ipn-intro-outside
I personally prefer Express Checkout to IPN. Both would work but express guarantees your customer will end up back on your website.