Hello there, I'm currently developing an application which has to be able to process PayPal Payments from multiple e-mails and then has to redirected to my IPN class located at my server. All the users of my application, have the possibility to set-up their own PayPal e-mail address into my system, and then the customers will pay directly to his PayPal Account (that means no intermediates). But there's a problem, I must ensure that my sellers are actually connected to my IPN. Why? Because if they are not, when a customer makes a payment, the transaction will be actually completed, but they won't be able to download their purchased item, because my application could not receive the params. So, the question is: how can I ensure this: User has a valid Paypal Account (based on e-mail) How do I know (and verify it each time) that this e-mail will sent a params directly to my server's IPN? (So important) How do I verify each time that some customer makes a purchase? In addition, I must say I also heard about the third party calls on the users behalf. If this is not possible, then it would be nice to setup for a party calls. But I don't know how to start. Any tips? Thank you so much guys!
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