Redirect s2members IPN URL to the PMPro IPN UR

my_ipn_redirect.php

/*
	Redirect s2members IPN URL to the PMPro IPN URL, e.g.
	https://yoursite.com/?s2member_paypal_notify=1 =>
	https://yoursite.com/wp-admin/admin-ajax.php?action=ipnhandler
*/
function my_ipn_redirect() {
	if(!empty($_REQUEST['s2member_paypal_notify']) && defined('PMPRO_DIR'))
	{
		require_once(PMPRO_DIR . "/services/ipnhandler.php");	
		exit;
	}
}
add_action('init', 'my_ipn_redirect');

This recipe is included in the blog post on "Redirect the s2member IPN URL to the PMPro IPN URL" at Paid Memberships Pro here: https://www.paidmembershipspro.com/redirect-the-s2member-ipn-url-to-the-pmpro-ipn-url/