At the same time, it's up to you to manage the messages you receive, saving and deleting as necessary. Otherwise you may find your mailbox inundated with mail, particularly if you subscribe to several active lists. A second difference is the quality of discussion. Thus there's less likelihood of trivial or repetitive discussion, which seems to be more common in newsgroups, particularly those that are unmoderated. Subscription to course discussion lists is usually limited to those whom the instructor authorizes, while course newsgroup postings can be read by anyone at Penn.
Web sites dedicated to related topics are one good source of list addresses.
A third is directories such as CataList , a searchable catalog of more than 8,000 public lists, and the Directory of Scholarly and Professional E-Conferences . You can look at the postings to see if you would be interested in subscribing. The examples in the next paragraph illustrate the use of the two addresses. New users frequently confuse them, and send their subscribe or unsubscribe commands to the posting address rather than to the administrative address. Majordomo-managed lists use similar commands.