If you don’t have IPN turned on already, enable it with http://yourwebsite.com as the notification url.
Note that when testing payments via PayPal Sandbox, your Sandbox seller account needs to have IPN enabled as well.
In SPP there are a two settings you can configure for this module:
Seller email – the email address where you’ll be receiving payments.
Primary email – enter only if if the seller email is different from your PayPal account’s primary email. For security reasons you will receive an alert if payment’s recipient doesn’t match your seller email or primary email.