Like in php it's possible to send a custom http response code, for example <?php header("HTTP/1.0 404 Not Found"); ?> PHP: How can this be done with asp. Especially a 503 error message.
here it may help you: blogs.msdn.com/david.wang/archive/2006/05/08/HOWTO-Useful-ASP-page-to-return-configurable-HTTP-Status-codes.aspx Response.Status = "503"