Ok... you need to use the Sandbox in order to test everything out first before you go live and get unexpected stuff... so check that box back then...
Go to
https://developer.paypal.com/ and sign up for an accout.
After you have an account you need to create test accounts (one for seller and one for buyer).
Put the test seller account's email in the business email box in nopCommerce. This should work now. The PTI identity token is something you have to go into the test seller account and get.
Go to
http://sandbox.paypal.com and sign in to your test seller account. Under "My Account" choose "Profile".
You should have links to the right under "Selling Preferences" - choose "Website Payment Preferences" then:
- Turn auto return on
- put your return URL in the box: http://www.yourdomain.com/PaypalPDTHandler.aspx
- Turn payment data transfer on and leave the rest alone
- hit "Save"
- go back to "Website Payment Preferences" and there should be an identity token there now under "Payment Data Transfer"... copy that and paste it into the PTI Identity token box in nopCommerce.
Now you're all set up to test!
Once you're done testing you just put in your real paypal email address there as well as the PTI token you create in your real account and you're good to go live.
Pretty much all of this is explained right on the configuration page in nopCommerce...
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