Hm, interesting. Normally setting Encrypted Website Payments to "Block Non-encrypted Website Payment: ON" in PayPal would block any PayPal checkout attempts coming from a third-party cart like ours, so we recommend turning that setting OFF for compatibility with our system.
That setting can seem a bit confusing, as it doesn't have anything to do with secure-encryption of checkout information like the buyer's personal data and payment account information, which we and PayPal ensure regardless of that setting. It only works with PayPal's own purchase button codes, to block payments from people who tamper with that button code (e.g., to change the item price, etc.).
E-junkie purchase button/link codes don't include any such details that buyers could tamper with in the first place; they just reference a seller's E-junkie Client ID and product Item Number, which our cart then uses to look up the item price and other details stored in our database.
We also perform a potential-fraud check when we receive IPN (Instant Payment Notification) from PayPal confirming a completed payment, to verify the price paid actually matches the item's current price setting in our database before we go ahead and process that order.
