RoundCube is a modern webmail solution which is easy to install and that runs on a standard PHP/MySQL configuration. The skins use the latest web standards such as XHTML and CSS 2. There are many exciting features RoundCube provides, for example, Multilingual capabilities, Full support of HTML, Find-as-you-type address book integration, Spell Checking and Complete customization with skins. RoundCube Webmail is released under the GPL License. Everyone is welcome to download and use it, deploy it and to re-distribute it.

Requirements: Server with PHP and mySQL
Demo: http://roundcube.net/?p=demo
License: GPL License