Roundcube - Free and Open Source Webmail Software

RoundCube is a free and open source browser based multilingual IMAP client with an application-like user interface. It supports functions like MIME support, address book, folder manipulation, message searching, spell checking and many more. It comes with a desktop like user interface with multiple skins and easy and customizable UI.

The most common features of Roundcube includes:

• Connectors
• Find-as-you-type address book integration
• Threaded message listing
• IDNA and SMTPUTF8 support
• Spell checking
• Shared/global IMAP folders
• Support for access control lists (ACL)
• Built-in caching for fast mailbox access
• Unlimited users and messages
• Import/export functions
• Plug-in API for flexible extensions
• XSS attack protection
• Support for PGP encryption
• Drag-&-drop message management
• Full support for MIME and HTML messages
• Multiple sender identities
• Full featured address book with groups and LDAP 
• Responsive skin (multi-device support)