I posted this a couple years ago
Here is what I did.... In the index.php where the maintenance area is I just used a simple redirect...
if( file_exists(ABS_PATH . '.maintenance') ) {
if(!osc_is_admin_user_logged_in()) {
require_once LIB_PATH . 'osclass/helpers/hErrors.php';
$title = sprintf(__('Maintenance » %s'), osc_page_title());
Change Red --- $message = sprintf(__('We are sorry for any inconvenience. %s is undergoing maintenance.') . '.', osc_page_title() );
To---- $message = sprintf(__('<meta http-equiv="Refresh" content="0; url=http://www.yoursite.com">') . '.', osc_page_title() );
header('HTTP/1.1 503 Service Temporarily Unavailable');
header('Status: 503 Service Temporarily Unavailable');
header('Retry-After: 900');
osc_die($title, $message);
Hope this helps others...