GNU Mailman is software that lets you manage electronic mailing lists. It supports a wide range of mailing list types, such as general discussion lists and announce-only lists. Mailman has extensive features which make it good for list subscribers, such as easy subscription and unsubscription, privacy options, and the ability to temporarily stop getting posts from the list. The list member features are covered in this document.
Mailman also has many features which make it attractive to list and site administrators. These features are covered in the list and site administrator manuals.