We need to verify new user email address with PayPal account through PayPal Account Authentication API.
Here are steps defined for this process:
1. New user will input email address in Registration Form in our website (which is equal to his / her PayPal account).
2. S/he will click on a button "Verify My PayPal Account".
3. S/he will redirect to PayPal Login page.
4. S/he will input email (which already automatically showing in Email address field); and password in PayPal password field.
5. When S/he clicks on "Log in" button, and entered fields are correct; s/he will redirect to our website and showing text "PayPal account has been verified".