In an open discussion group, anyone can post and read messages. In a moderated group, a moderator reviews the messages before they become public. If the moderator approves the message, it is forwarded to the discussion group and posted. If the moderator does not approve the message, an e-mail message is sent to the originator, explaining why the message was not accepted. Another advantage of having a moderated discussion group is that the moderator can combine messages and posts into a single message, or digest, that is sent out periodically.
Digests are also a good way to archive messages.
If you decide to set up moderated discussion groups, you should choose moderators who are involved with the subject matter being covered by the group. You should also define the time commitment required to be a moderator. Of course, how often the moderator checks for messages is a matter to be decided by that person and his or her immediate supervisor. Depending on the amount of information your discussion groups contain and how long this information will be kept before being deleted, you may want to consider indexing. Indexing allows full-text searching of one or more groups without the users having to read each individual message or header.