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Mailing List Design - List Types

One might also elect to have the campus wide area network liaison screen the messages in either case and only forward those which are considered of merit.

- E. Krol; The Hitchhikers Guide to the Internet; RFC 1118; Sept. 1989.

There are three general types of mailing lists, each with a different type of operation:

  • Unmoderated. These allow any subscriber to send an email to the mailing list for distribution to all subscribers, in real-time without any pre-screening. Most lists are unmoderated.
  • Moderated. These lists have a moderator, a human being that checks all email sent to the list to make sure it does not contain inappropriate content before the server distributes it to subscribers. There are more of these lists than there used to be because of problems with spam email, but they usually have fewer members and lower traffic, because it takes a lot of time for a moderator to read and check all of the incoming email on a high traffic list, so the size of a moderated list is somewhat self limiting.
  • One-way. These lists are used to distribute information from a central source. Only one person or organization can send email to the list for distribution to all subscribers. These types of lists are often used by organizations to distribute information. There aren't many of these lists, but they often have a very great many members, in some cases hundreds of thousands. A typical example of a one-way list is NewsScan, which sends an email on developments in information technology to subscribers several times a week.