They are not email based, but they are messages publicly posted on the net for all to access.
Mailing lists are discussions that are email based.
Messages are sent to your email address. UseNet Newsgroups Usenet News is a global bulletin board system consisting of a wide range of interest groups. People on the Internet can communicate with each other by reading and contributing messages to the groups in which they are interested. Messages are written by people who are giving their opinion on a subject. Be careful of the validity of what is said in a newsgroup.