Allows site administrators to accept payments using PayPal payment system.

IPN

In order to use the IPN feature of PayPal API, you should have the "Business" account on PayPal and set appropriate options on paypal.com.

1. Login to paypal.com
2. Choose "My Account" tab
3. Choose "Profile" menu item
4. Once the new page opened, choose "My selling tools" link on the left menu
5. There would be a grouped list, click "Update" link next to the "Instant payment notifications" parameter
6. At the newly opened page, click the "Choose IPN Settings" button
7. There would be a tiny form with options. Fill them as follows:

   Notification URL: http://{YOUR_SUBRION_SITE_URL}/ipn/paypal/
   (say, http://example.com/ipn/paypal/ for EXAMPLE.COM domain, respectively)

   IPN Messages: "Receive IPN messages (Enabled)" option

8. Click "Save" button

NOTE: Some of these items may be missing if the type of your PayPal account differs from "Business".