public function send_tickets_email( $order_ref ) {
		$order_id = $order_ref instanceof WC_Order
			? $order_ref->get_id()
			: $order_ref;


		update_post_meta( $order_id, $this->mail_sent_meta_key, '1' );

		// Ensure WC_Emails exists else our attempt to mail out tickets will fail
		WC_Emails::instance();

		/**
		 * Fires when a ticket order is complete.
		 *
		 * Back-compatibility action hook.
		 *
		 * @since 4.1
		 *
		 * @param int $order_id The order post ID for the ticket.
		 */
		do_action( 'wootickets-send-tickets-email', $order_id );
	}