Roundcube Webmail Client

Roundcube is a browser-based multilingual IMAP email client with an application-like user interface, providing full email functionality through a web browser. Originally developed by Thomas Bruederli in 2005, with a full rewrite as Roundcube Next, the project has been widely deployed by ISPs, universities, and hosting providers. Key features include: IMAP support (full IMAP4rev1 protocol compliance with folder management, message flagging, thread sorting, and server-side search), SMTP integration (configurable SMTP server for outgoing mail with authentication and TLS), rich text editor (HTML email composition with CKEditor integration, inline images, and signature management), address book (contact management with groups, import and export via vCard, LDAP integration, and auto-complete), message threading (conversation view grouping messages by subject and references), keyboard shortcuts (extensive keyboard navigation for efficient email management), search (full-text message search with filtering by date, sender, subject, and flag status), PGP encryption (Enigma plugin for OpenPGP encryption and signing using GnuPG), calendar and tasks (Kolab plugins for calendar, task management, and file sharing), plugin system (over 200 community plugins extending functionality with password change, two-factor authentication, and custom skins), localization (over 80 languages with right-to-left support), skin system (responsive HTML and CSS themes with customizable templates), and caching (database-backed message caching with MySQL, PostgreSQL, SQLite, and SQL Server support).