Show list of Koozali outstanding bugs: [here](https://bugs.koozali.org/buglist.cgi?component=roundcube-plugin-html5_notifier&product=SME%20Server%2011.X&query_format=advanced&limit=0&bug_status=UNCONFIRMED&bug_status=NEW&bug_status=ASSIGNED&bug_status=REOPENED&bug_status=CONFIRMED)
It displays Desktop Notifications like the ones you might know from Google Mail. Just keep Roundcube opened in a (minimized) tab and enjoy getting notifications every time a new mail arrives.
It just works in modern browsers like Google Chrome, SRWare Iron or Firefox, because "Desktop Notification" is a new feature in HTML5.