Post IPN data to multiple URLs example [Paid Memberships Pro]

pmpro-ipn-redirect.php

<?php
/**
 * Forward IPN requests from WooCommerce PayPal Standard to also send to Paid Memberships Pro.
 * Please change the URL on line 9 to match that of your Paid Memberships Pro site URL.
 * Follow this guide to add this to your site - https://www.paidmembershipspro.com/create-a-plugin-for-pmpro-customizations/
 */
function my_pmpro_forward_ipn() {	
	if ( isset( $_REQUEST['callback'] && $_REQUEST['callback'] == 'gravityformspaypal' ) {		
		$fp = wp_remote_post( 'https://saac-arts.org/wp-admin/admin-ajax.php?action=ipnhandler', $_POST );
	}	
}
add_action('wp_ajax_nopriv_ipnhandler', 'my_pmpro_forward_ipn', 5);
add_action('wp_ajax_ipnhandler', 'my_pmpro_forward_ipn', 5);