Toolbox - Send email when customer skips next payment

functions.php

<?php

/**
 * Send an email notification when a customer skips a subscription shipment.
 *
 * @param $subscription
 * @param $user_id
 * @param $old_next_date
 * @param $next_payment_date
 */
function sp_toolbox_notify_skip( $subscription, $user_id, $old_next_date, $next_payment_date ) {
	$to      = ''; // recipient of the email
	$subject = 'Customer Skipped Subscription'; // subject
	$body    = 'Subscription ID: ' . $subscription->get_id() . '<br/>' . PHP_EOL; // Subscription ID
	$body   .= 'Customer User ID: ' . $user_id . '<br/>' . PHP_EOL; // User ID
	$body   .= 'Old Date: ' . $old_next_date . '<br/>' . PHP_EOL; // The old next payment date
	$body   .= 'Next Date' . $next_payment_date . '<br/>' . PHP_EOL; // The new next payment date
	$headers = array( 'Content-Type: text/html; charset=UTF-8' );

	wp_mail( $to, $subject, $body, $headers );
}
add_action( 'jgtb_after_skip_next_date', 'sp_toolbox_notify_skip', 10, 4 );