Integrate multiple Instant Payment Notification (IPN) tools into your site with the Stellar IPN Relay for PayPal. The IPN Relay forwards IPN transaction data to an unlimited number of IPN processors. Requires PHP 4+ Integrate all your PayPal IPN processing systems together. Mix shopping cart, shipping tracking and digital goods delivery systems from different vendors. Supports PayPal Website Payments Standard (WPS) and Instant Payment Notifications (IPN). No database required. Supports IPN status codes - processing errors with forwarded IPN processors are reported back to PayPal so that transactions will be resent on failure.