E-mail lists are designed to distribute mail from any member of the list to all its members or subscribers. There are over 2,000 such lists open to the public, each focussing on a topic of common interest.
Topics vary widely in the range of general interest.
Usually a really active list has 10 or 20 experts who are willing to answer questions, and ask good ones, who do most of the posting. The knowlege, preferences, theories, prejudices, and other aspects of these posters' personalities are pretty evident. The messages are sorted by thread , that is by the topic announced in the subject line. A thread may spin a tangent and these subject lines may, a few days after their inception, conceal discussions of the future of audiotape, medieval footnote forms, or the 1992 Winter Olympics. The software responds to messages that are subscriptions or signoffs by modifying the list of members, and posts messages to all members on the current list.