public void greet(String server) {
        if (heloResponse != null || ehloResponse != null)
            return;
        int code = ehlo(server).code;
        if (code >= 200 && code < 300)
            return;
        Response response = helo(server);
        if (response.code < 200 || response.code > 299)
            throw new SMTPException(response);
    }