Authentication using Jakarta mail api

I am trying to develop a Gmail clone, I have integrated the email sending process and all. I just want to integrate an email authentication system.

Session session = Session.getInstance(props,
      new javax.mail.Authenticator() {
        protected PasswordAuthentication getPasswordAuthentication() {
            return new PasswordAuthentication(username1, password);
        }
      });

I want to send this session to Gmail to authenticate the email. But I couldn't find a way to do so.