In practice, this means you will almost never see an ad posted on its own merits. Messages must be no longer than 15 kilobytes in length. Posters are strongly encouraged to post summaries and direct readers to websites or similar external sources in lieu of posting entire resources verbatim to the list. Responses to messages should, whenever possible, include only enough of the previous post to continue the thread of the discussion. If your email software makes it impossible to do this, you may have to explain this to the moderators.
Instructions are below.
In practice, unless you attempt to forward a graphic or an encoded or word-processed document to the list, you will not have to worry about this rule. No four-letter words or ad hominem attacks. You may criticize a policy or a point of view, but you must substantiate your comments. It is the responsibility of the poster to ensure that his or her post does not violate copyright law. Threads that have run their course but refuse to die may be terminated by the moderators.