As Handel said, this is not what you need. However, the alternative is to make authorization in the amount of $ 1 using express verification. Set PAYMENTREQUEST_0_PAYMENTACTION = Authorization, extract the token and redirect the user to agree to authorization for $ 1. After redirecting to your website, you will receive a PayerID, which you can use to call GetExpressCheckoutDetails and get some (definitely not all) of the information.
For instance. first and last name and email address. In addition, you will know that he has a working source of funding.
Once you are satisfied, you can call DoVoid to revoke the authorization of $ 1, and the user will not be charged at all.