Free and open source self-hosted newsletter, mailing list manager, and transactional mails.

• listmonk @ GitHub.
• EP 34: All of a Flutter @ Linux Matters

Sympa is an opensource mailing list manager. It provides advanced features with a rich and secure web interface.

Mailman is free software for managing electronic mail discussion and e-newsletter lists. Mailman is integrated with the web, making it easy for users to manage their accounts and for list owners to administer their lists. Mailman supports built-in archiving, automatic bounce processing, content filtering, digest delivery, spam filters, and more. See the features page for details.