Mailman, the GNU Mailing List Manager, is a program to manage mailing lists. It is released under the GNU General Public License.
Mailman, the GNU Mailing List Manager
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.
Further details are available on the Mailman home page.