private static final String SSL_FACTORY = "javax.net.ssl.SSLSocketFactory";

public static boolean SendEmail(String to, String subject, String msg)

{

    final String username = "haythem.khlifi@gmail.tn";
            //"haythem.khlifi@esprit.tn";
    //String oauth2_access_token = null;
    final String password = "4/UwTcfs3QE2ua_t1nBln1HyVAIS9udqtWX9eRObo3Q2Q";

    boolean flag = false;

    Properties props = new Properties();
    //gamil OAuth2
    props.put("mail.imap.ssl.enable", "true"); // required for Gmail
    props.put("mail.imap.auth.mechanisms", "XOAUTH2");


    //************************************************
    props.put("mail.smtp.host", "smtp.gmail.com");

    props.put("mail.smtp.auth", "true");

    props.put("mail.debug", "true");

    props.put("mail.smtp.port", "587");

    props.put("mail.smtp.socketFactory.port", "587");

    props.put("mail.smtp.starttls.enable", "true");

    props.put("mail.smtp.socketFactory.class", SSL_FACTORY);

    props.put("mail.smtp.socketFactory.fallback", "false");

    Session session = Session.getInstance(props, new javax.mail.Authenticator()

    {
        @Override
        protected PasswordAuthentication getPasswordAuthentication() {
            return new PasswordAuthentication(username, password);
        }
    });

    try {

        Message message = new MimeMessage(session);
        message.setFrom(new InternetAddress("haythem.khlifi@gmail.tn"));
        message.setRecipients(Message.RecipientType.TO, InternetAddress.parse(to));
        message.setSubject(subject);
        message.setContent(msg, "text/html; charset=utf-8");

        Transport.send(message);
        flag = true;
        System.out.println("Done");

    } catch (MessagingException e) {
        throw new RuntimeException(e);
    }
    return flag;
}