GNU Mailman is software to help manage email discussion lists and e-newsletters. Its integrated Web interface provides easy-to-use access for list members and list administrators. Mailman supports built-in archiving, automatic bounce processing, content filtering, digest delivery, spam filters, topics, Usenet gateways, and more. It is fully internationalized, and supports digests and email commands. It runs on any Linux or Unix-like operating system and is compatible with most email and Web servers, mail readers, and Web browsers.
The `other' Mailman
We know about this product, but it's not a mailing list manager,
so we're not worried about it.