'Create an envelope and a message receiver for the relay queue.
@type user: L{User}
@param user: A user.
@rtype: L{IMessage <smtp.IMessage>}
@return: A message receiver.'

def startMessage(self, user):

    queue = self.service.queue
    (envelopeFile, smtpMessage) = queue.createNewMessage()
    with envelopeFile:
        log.msg(('Queueing    mail    %r    ->    %r' % (str(user.orig), str(user.dest))))
        pickle.dump([str(user.orig), str(user.dest)], envelopeFile)
    return smtpMessage
