WC_Emails::init_transactional_emails PHP Method

    public static function init_transactional_emails()
    {
        $email_actions = apply_filters('woocommerce_email_actions', array('woocommerce_low_stock', 'woocommerce_no_stock', 'woocommerce_product_on_backorder', 'woocommerce_order_status_pending_to_processing', 'woocommerce_order_status_pending_to_completed', 'woocommerce_order_status_pending_to_cancelled', 'woocommerce_order_status_pending_to_failed', 'woocommerce_order_status_pending_to_on-hold', 'woocommerce_order_status_failed_to_processing', 'woocommerce_order_status_failed_to_completed', 'woocommerce_order_status_failed_to_on-hold', 'woocommerce_order_status_on-hold_to_processing', 'woocommerce_order_status_on-hold_to_cancelled', 'woocommerce_order_status_on-hold_to_failed', 'woocommerce_order_status_completed', 'woocommerce_order_fully_refunded', 'woocommerce_order_partially_refunded', 'woocommerce_new_customer_note', 'woocommerce_created_customer'));
        foreach ($email_actions as $action) {
            add_action($action, array(__CLASS__, 'send_transactional_email'), 10, 10);
        }
    }