Effective Systems, LLC - PayPal Standard Enhanced Plugin
The PayPal Standard Plugin from nopCommerce has 2 address parameters that are passed to PayPal that impact what happens on the PayPal site. The way these parameters are hard coded into the plugin can cause PayPal to reject the login if the customers shipping address is not valid.
This enhanced version of the plugin from Effective Systems, LLC allows you to configure those 2 parameters in the admin panel of nopCommerce. The two parameters are shown here:

Use address override:
These descriptions are based on the “Account Optional” setting in your PayPal account profile being turned on. (Which allows customers to pay with a Credit Card without having / signing up for a PayPal account)
- If set on, this overrides the address that PayPal has with the address being passed in from nopCommerce. If there’s an error, the address cannot be modified, and PayPal rejects the login; so the payment will not happen.
- If set to off, then the address used is the address stored in PayPal.
Select shipping address mode:
This setting designates how to prompt the buyer for shipping address. Allowed values are:
- Optional : buyer is prompted to include a shipping address.
- Do not prompt : buyer is not asked for a shipping address
- Required : buyer must provide a shipping address
Recommended settings:
Address Override = off
Shipping Address Mode = Do not prompt
This would eliminate the need for address validation on PayPal, and since nopCommerce collects and stores the shipping address, you really do not see the need to pass it to PayPal for payment processing.