On PayPal's webiste there's an Account Profile that allows you to enable Encrypted Website Payments, and therefore Block Non-encrypted payments.
I'm unsure whether to enable this.
My question is, does the nopCommerce checkout encrypt payments?
I notice there is a private key encryption in the nopCommerce Admin area but I understand this is to do with the database rather than payments sent to a payment gateway.
I couldn't find that feature. I don't think that has ever been an issue in the time I have been using PayPal. Since 2005. We only Use Paypal express and the virtual terminal and have never had to use "encrypted website payments" Just to help you a little though, call the PayPal support line and when it ask you to "say" , say "help". It will ask you to repeat or want you to pick another option but just say "help" again and it will send you to a "real" person. That is how I get answers from PayPal and they usually very helpful.