An example of security by obscurity applied to usenet newsgroups. Also known as "self moderation."

Moderated newsgroups are groups with messages (or posts) with a mandatory "Approved:" header in the message. The header follows RFC 822 specifications and a group's moderators can ensure only valid messages appear in their group by checking this header's content. An automoderated group typically requires all participants to add an "Approved:" header, regardless of the header's content. For example, these headers came from a recent post to alt.sysadmin.recovery:

Newsgroups: alt.sysadmin.recovery
Subject: (omitted to protect the guilty)
Approved: Hah!

Most "off-the-shelf" newsgroup software (such as Outlook Express) does not allow the user to arbitrarily add headers to messages. As a result, participants of automoderated groups must use other software, such as tin or a command-line NNTP client capable of posting plain text documents.

Automoderation may result in a better signal to noise ratio in these groups, though nothing stops a troll or spammer from using these other clients to post to an automoderated group. In fact, Macintosh users have an easier time posting to automoderated groups with system extensions such as Internet Config, as Internet Config is capable of adding headers to newsgroup postings regardless of what client software the participant uses.