javax.mail验证电子邮件登录是否正确

你好，我需要验证我的电子邮件登录是否正确

 Properties props = new Properties();  
    props.put("mail.smtp.host", "smtp.gmail.com");  
    props.put("mail.smtp.auth", "true");  
    props.put("mail.debug", "true");  
    props.put("mail.smtp.port", 25);  
    props.put("mail.smtp.socketFactory.port", 25);  
    props.put("mail.smtp.starttls.enable", "true");
    props.put("mail.transport.protocol", "smtp");

    Session mailSession = null;

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

当登录不存在时？我如何才能得到登录不正确？示例填写错误密码等。谢谢