Roundcube — Self-Hosted Webmail with a Modern Interface

Introduction

Roundcube is a mature open-source webmail client written in PHP. It provides a desktop-like email experience in the browser, connecting to any IMAP server. It has been a staple of self-hosted email for over a decade, offering a polished UI with drag-and-drop, rich text composing, and a plugin system for extended functionality.

What Roundcube Does

• Connects to any IMAP mail server and provides a web-based email client
• Supports rich text composing with inline images and HTML signatures
• Manages folders, filters, and server-side message rules (Sieve/ManageSieve)
• Includes an address book with LDAP, CardDAV, and local contact storage
• Provides full-text search across messages with server-side indexing

Architecture Overview

Roundcube is a PHP application that communicates with IMAP and SMTP servers using standard protocols. The frontend is built with jQuery and a custom UI framework that provides a responsive, multi-pane layout. Session and cache data can be stored in MySQL, PostgreSQL, or SQLite. The architecture is stateless per request, making it easy to scale behind a load balancer.

Self-Hosting & Configuration

• Deploy via Docker, apt packages on Debian/Ubuntu, or from the PHP source archive
• Configure IMAP and SMTP server addresses in config.inc.php
• Set up MySQL, PostgreSQL, or SQLite for session and cache storage
• Install plugins by dropping them into the plugins/ directory and enabling in config
• Place behind Apache or Nginx with PHP-FPM for production

Key Features

• Drag-and-drop message management with multi-folder support
• ManageSieve integration for server-side email filtering rules
• Responsive design adapts to tablets and mobile screens
• Spell checking with multiple language support
• Extensible through plugins for calendars, 2FA, themes, and more

Comparison with Similar Tools

• RainLoop / SnappyMail — lighter webmail clients with fewer features; Roundcube is more mature and extensible
• SOGo — groupware with webmail, calendar, and contacts; heavier but broader feature set
• Zimbra — full email and collaboration suite; Roundcube is a standalone client connecting to any IMAP server
• Horde — PHP groupware framework; Roundcube focuses specifically on being a great email client
• K-9 Mail / Thunderbird — native apps; Roundcube provides browser-based access without installing software

FAQ

Q: Does Roundcube include a mail server? A: No. Roundcube is a web client only. You need a separate IMAP/SMTP server like Dovecot and Postfix.

Q: Can I use Roundcube with Gmail or other providers? A: Yes. Roundcube connects to any IMAP server, including Gmail, Outlook, and custom mail servers.

Q: How do I add two-factor authentication? A: Install the twofactor_gauthenticator plugin to add TOTP-based 2FA to the login process.

Q: Is Roundcube still actively maintained? A: Yes. Roundcube continues to receive regular updates, security patches, and community plugin development.

Sources

• https://github.com/roundcube/roundcubemail
• https://roundcube.net/about