A Mailing List would be a list to which many Users are subscribed and whenever an authorized User posts to the Mailing List, all subscribers would receive the message.

b2evolution allows something similar, but doesn’t call it a "Mailing List".

In b2evolution, interested Users can subscribe to a Collection (which could be a news blog with a reduced posters or a forum with many possible posters). Then, whenever some autorized posts into that Collection, the Subscribers receive an email notification (which may contain the full text of the post or not).