function fflcommerce_send_customer_invoice($order_id)
{
    $order = new fflcommerce_order($order_id);
    fflcommerce_emails::send_mail('send_customer_invoice', get_order_email_arguments($order_id), $order->billing_email);
}
function jigoshop_send_customer_invoice($order_id)
{
    $order = new jigoshop_order($order_id);
    jigoshop_emails::send_mail('send_customer_invoice', get_order_email_arguments($order_id), $order->billing_email);
}