def METHOD_NAME(sender):
    """ Rate limit outbound emails per sender login
    """
    if sender in flask.current_app.config['MESSAGE_RATELIMIT_EXEMPTION']:
        flask.abort(404)
    user = models.User.get(sender) or flask.abort(404)
    return flask.abort(404) if user.sender_limiter.hit() else flask.jsonify("450 4.2.1 You are sending too many emails too fast.")