Sympa

Sympa is an open-source mailing list management system that automates subscriptions, moderation, message distribution and archive management. It provides web, command-line and SOAP interfaces and is designed to scale to large mailing lists.

Key Features

• Automated list lifecycle: subscription, unsubscription, moderation, role management and templated notifications.
• WWSympa web interface for list management and public archives, plus a command-line toolset for administration.
• SOAP API (WSDL) for integration with external systems and single-sign-on scenarios.
• Support for multiple RDBMS backends (MySQL/MariaDB, PostgreSQL, SQLite, Oracle) to store preferences, passwords and list metadata.
• Compatible with standard MTAs (Postfix, Sendmail, Exim, OpenSMTPD) and common HTTP servers (Apache, nginx, lighttpd); designed for batch/message queue daemons to handle high-volume delivery.
• Advanced message workflow: archiving, message batching, bounce handling, moderation queues and customizable authorization scenarios.
• Internationalization, template customization, extensive configuration hierarchy and a broad set of optional Perl modules to extend functionality.
• Security and deliverability features including DKIM/ARC-related handling and configuration options for spam mitigation.

Use Cases

• University or large-organization mailing lists for announcements, courses and department communications.
• Open-source projects and community hubs needing archived discussions, moderation and subscription workflows.
• Newsletters and large-distribution mailings where queued delivery, bounce management and templated messaging are required.

Limitations and Considerations

• Requires a POSIX-compatible system and Perl 5 (Perl 5.16.0 or later recommended); Microsoft Windows is not supported.
• Installation and operation depend on numerous external Perl modules and system components (database server, MTA, HTTP server), which can increase setup complexity.

Sympa is a mature, feature-rich mailing list manager focused on configurability and scale. It is well-suited where detailed list policies, integration and high-volume delivery are required.