'Fail because authentication is required, but the server does not support
any schemes we support.
@param code: The server status code from the most recently received
server message.
@type code: L{int}
@param resp: The server status response from the most recently received
server message.
@type resp: L{bytes}'

def esmtpAUTHRequired(self, code=(-1), resp=None):

    tmp = []
    for a in self.authenticators:
        tmp.append(a.getName().upper())
    auth = ('[%s]' % ',    '.join(tmp))
    self.sendError(AUTHRequiredError(502, ('Server    does    not    support    Client    Authentication    schemes    %s' % auth), self.log.str()))
