如何使用JavaMail接口监听身份验证错误？

Properties props = new Properties();
props.put("mail.smtp.host", "smtp.example.com");
props.put("mail.smtp.port", "587");
props.put("mail.smtp.auth", "true");

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

Transport transport = session.getTransport("smtp");

transport.addTransportListener(new TransportListener() {
    public void messageDelivered(TransportEvent event) {
        // 邮件发送成功
    }

    public void messageNotDelivered(TransportEvent event) {
        // 邮件发送失败
    }

    public void messagePartiallyDelivered(TransportEvent event) {
        // 部分邮件发送成功，部分邮件发送失败
    }

    public void commandStarted(TransportEvent event) {
        // 发送命令开始
    }

    public void commandSucceeded(TransportEvent event) {
        // 发送命令成功
    }

    public void commandFailed(TransportEvent event) {
        // 发送命令失败
        if (event.getType() == TransportEvent.ALERT) {
            // 身份验证错误
        }
    }
});

Message message = new MimeMessage(session);
message.setFrom(new InternetAddress("sender@example.com"));
message.setRecipients(Message.RecipientType.TO, InternetAddress.parse("recipient@example.com"));
message.setSubject("Test Email");
message.setText("This is a test email.");

transport.connect();
transport.sendMessage(message, message.getAllRecipients());
transport.close();