leaky-paywall-failed-payment.php

<?php

add_action( 'leaky_paywall_failed_payment', 'zeen101_send_payment_failed_notification' );

function zeen101_send_payment_failed_notification( $user ) {

	$to = $user->user_email;
	$subject = 'Your payment has failed';
	$body = 'We are sorry to inform you that your attempt at payment has failed. Please <a href="https://examplesite.com/my-account/">log in to your account</a> on Example Site and update your credit card information.';
	$headers = array('Content-Type: text/html; charset=UTF-8','From: Example Site <[email protected]>');
	 
	wp_mail( $to, $subject, $body, $headers );

}