FREE Round Cube Mail

This project is a free and open source webmail solution with a desktop-like user interface which is easy to install/configure and that runs on a standard LAMPP server. The skins use the latest web standards such as XHTML and CSS 2. Roundcube includes other sophisitcated open-source libraries such as PEAR, an IMAP library derrived from IlohaMail the TinyMCE rich text editor, Googiespell library for spell checking or the WasHTML sanitizer by Frederic Motte.

Released features
Available in 67 languages
Drag-&-drop message management
Full support for MIME and HTML messages
Sophisticated privacy protection
Compose messages with attachments
Multiple sender identities
Address book with groups and LDAP connectors
Find-as-you-type address book integration
Richtext/HTML message composing
Forwarding messages with attachments
Searching messages and contacts
Threaded message listing
Spell checking
IMAP folder management
Support for external SMTP server
Built-in caching for fast mailbox access
Unlimited users and messages
Template system for custom skins
Plug-in API for flexible exensions

Server Requirements
Apache or Lighttpd webserver
PHP Version 5.2.1 or greater
MySQL, PostgreSQL, SQLite or MSSQL database
An IMAP server which supports IMAP4 rev1
An SMTP server (recommended) or PHP configured for mail delivery