1. Open your Spaces's Settings:
2. Click Payment Methods, and then click Manage:
3. Select PayPal from the drop-down menu, and then click Modify to get your PayPal IPN URL.
4. After you have yourPayPal IPN URL, you need to enter it into your PayPal account details: https://www.paypal.com/ca/cgi-bin/webscr?cmd=_profile-ipn-notify-edit