In most cases you will receive a short description including the purpose of the list and the audience for which it is intended. I will use another example here. Lists in the area of literature may cover national literatures, individual authors, literary theory or information about how to write. They may be geared to scholars, graduate students or the general reader.
The following is a description of AUSTEN-L:
"A moderated digest for readers of Jane Austen. If you enjoy Jane Austen's novels and those of her contemporaries, such as Fanny Burney, Maria Edgeworth and Maria Wollstonecraft, you might want to exchange views with others on any aspect of her work and her time."
Some Lists have a person who manages the list messages. The moderator reviews all messages and may not distribute those determined inappropriate.
You are sometimes given the option of receiving your messages in digest form. This means that they are batched and sent all at one time, for example one delivery daily, rather than as they are received. The digest can be a great time saver if you have selected a very active list