AUTHINFO is used to inform a server about the identity of
    a user of the server. In all cases, clients must provide
    this information when requested by the server. Servers are
    not required to accept authentication information that is
    volunteered by the client. Clients must accommodate servers that
    reject any authentication information volunteered by the client.

    There are three forms of AUTHINFO in use. The original version,
    an NNTP v2 revision called AUTHINFO SIMPLE and a more recent
    version which is called AUTHINFO GENERIC.