There may be occasions when you will make your Joomla! website completely unavailable to visitors for a short time. There is a simple switch in the Administrator back-end that enables you to take your website offline very quickly. It can be returned to service at a later time just as easily.
To make your Joomla! website unavailable to visitors, replacing it with a simple message, do this:
Anacron comes with it's own customized Site Offline page which is displayed when the site is set to Offline Mode within the Joomla! Administration. This page, /templates/rt_anacron/offline.php can be easily customised with your own layout, logo and colours, so it represents a message which relates to your project.