The LISTS command returns an index describing the mailing lists
    that the mail server handles. This description might not give
    the names of each and every available mailing list; for such
    information use the DIRECTORY/LIST command. The index is, more
    often than not, a simple description of the mailing lists handled
    by the server. It might also describe any policies associated
    with the lists (e.g., who can subscribe, how to post to the list,
    etc.).