如何使用线程在Java中发送电子邮件？

Question

如何使用线程发送电子邮件？我写了下面的代码，但是没有用。它不会引发任何异常，但是我也没有收到电子邮件。如果我不使用线程，则代码可以正常工作。有什么问题吗？

    final String username = "admin@gmail.com";
    final String password = "admin";

    new Thread(()-> {
        Properties props = new Properties();
        props.put("mail.smtp.host", "smtp.gmail.com");
        props.put("mail.smtp.socketFactory.port", "465");
        props.put("mail.smtp.socketFactory.class", "javax.net.ssl.SSLSocketFactory");
        props.put("mail.smtp.auth", "true");
        props.put("mail.smtp.prot", "465");

        Session session = Session.getDefaultInstance(props,
                new Authenticator() {
                    protected PasswordAuthentication getPasswordAuthentication() {

                        return new PasswordAuthentication(username, password);
                    }
                }
        );
        try {
            Message message = new MimeMessage(session);
            message.setFrom(new InternetAddress(username));
            message.setRecipients(Message.RecipientType.TO, InternetAddress.parse(recipient));
            message.setSubject(subject);
            message.setText(text);
            Transport.send(message);

        } catch (Exception e) {
            System.out.println("Something is wrong!");
        }
    }).start();