The part preceding the boldface can be ignored in this case. The lists can reach up to hundreds or thousands of people with mutual interests. This may sound restrictive, but in reality there are few situations where post content is censored or edited. Most people are not very concerned about this, but public discussions of potentially illegal actions such as trading tapes, bootlegs or otherwise is at your own risk and should probably be undertaken with some discretion. In theory, mailing lists can reach a lot of people who have email but cannot get Internet news.
Mailing lists tend to have less usless posts and flames because of a smaller, more focused audience.
Ergo, Bill Bruford is the social epicentre of the human race. Quite frightening really. Save the introduction to any list to which you subscribe or keep track of the administration address when you want to unsubscribe. Many people post subscribe and unsubscribe messages to the list mailer addresses, unwittingly sending them to up to hundreds of other subscribers. Some list administrators do not regularly read the mailing list posts or have automated the subscription process, so use the administration address for the appropriate requests.