RoundCube Technology Intelligence

What is Roundcube?

Roundcube is a free, open-source webmail client written in PHP. First released in 2005, it provides a desktop-like email experience in the browser with features comparable to desktop email clients like Outlook or Thunderbird. It connects to mail servers via IMAP and sends mail through SMTP.

The interface uses AJAX for responsive interactions without full page reloads, supporting drag-and-drop, keyboard shortcuts, and rich text editing. Roundcube includes an address book, folder management, message searching, and spell checking out of the box.

Roundcube is widely deployed by hosting providers, universities, and businesses as their webmail solution. Its plugin architecture allows extensive customization, from custom themes to integration with calendars, file managers, and two-factor authentication systems.

Roundcube Features

IMAP/SMTP: Full IMAP support. SMTP sending. Multiple identities. Server-side folders. Message threading.

Rich Composer: HTML and plain text. Inline images. Attachments. Draft saving. Spell checking. Templates.

Address Book: Contact management. Groups. vCard import/export. LDAP integration. Multiple address books.

Search: Full-text search. Server-side search. Saved searches. Quick filters. Multi-folder search.

User Interface: Responsive design. Three-column layout. Keyboard shortcuts. Customizable skins. Dark mode.

Security: PGP/GPG encryption. S/MIME support. Two-factor auth plugins. Password policies. Secure sessions.

Roundcube Use Cases

Hosting Providers: cPanel webmail. Shared hosting email. Reseller packages. Managed email services.

Enterprise Email: Corporate webmail access. Remote email access. Browser-based mail. Cross-platform access.

Educational Institutions: Student email portals. Faculty communication. Campus mail systems. Alumni services.

Government: Secure internal mail. Agency communication. Regulatory compliance. Audit trail requirements.

Self-Hosted Email: Privacy-focused setups. Personal mail servers. Family email. Small business email.

ISP Services: Customer webmail. Bundled email services. Premium mail offerings. Value-added services.

Roundcube Code Examples

Configuration

// config/config.inc.php
$config['db_dsnw'] = 'mysql://roundcube:password@localhost/roundcubemail';

// IMAP Settings
$config['default_host'] = 'ssl://mail.example.com';
$config['default_port'] = 993;
$config['imap_auth_type'] = 'LOGIN';

// SMTP Settings
$config['smtp_server'] = 'tls://mail.example.com';
$config['smtp_port'] = 587;
$config['smtp_user'] = '%u';
$config['smtp_pass'] = '%p';

// Interface Settings
$config['skin'] = 'elastic';
$config['language'] = 'en_US';
$config['enable_spellcheck'] = true;
$config['spellcheck_engine'] = 'pspell';

// Security
$config['force_https'] = true;
$config['session_lifetime'] = 30;
$config['ip_check'] = true;

Plugin Example

// plugins/myplugin/myplugin.php
class myplugin extends rcube_plugin {
    public function init() {
        $this->add_hook('message_compose', array($this, 'compose_handler'));
        $this->register_action('myplugin.action', array($this, 'action_handler'));
    }

    function compose_handler($args) {
        // Modify compose behavior
        return $args;
    }
}

Roundcube Benefits

Open Source: GPL license. Free to use. Community development. No vendor lock-in. Transparent code.

Feature-Rich: Desktop-class features. Full email management. Address book. Folder organization.

Extensible: Plugin system. Custom skins. Hook-based architecture. Third-party integrations.

Standards Compliant: IMAP4rev1. SMTP. MIME. HTML5. Accessibility standards.

Widely Supported: Large user base. Active development. Extensive documentation. Community forums.

Easy Deployment: PHP based. MySQL/PostgreSQL/SQLite. Standard hosting compatible. Docker available.