ExecutorService executorService = Executors.newFixedThreadPool(10);

executorService.execute(new Runnable() {
    @Override
    public void run()
    {
        try {
            SendEmailUtility.sendmail("xxx@gmail.com");
        } catch (IOException e) {
            logger.error("failed", e);
        }
    }
});

public class SendEmailUtility
{
    public static String sendmail(String sendto)
        throws IOException
    {
        String result = "fail";
        Properties props_load = getProperties();
        final String username = props_load.getProperty("username");
        final String password = props_load.getProperty("password");
        Properties props_send = new Properties();
        props_send.put("mail.smtp.auth", "true");
        props_send.put("mail.smtp.starttls.enable", "true");
        props_send.put("mail.smtp.host", props_load.getProperty("mail.smtp.host"));
        props_send.put("mail.smtp.port", props_load.getProperty("mail.smtp.port"));

        Session session = Session.getInstance(props_send,
            new javax.mail.Authenticator() {
                @Override
                protected PasswordAuthentication getPasswordAuthentication()
                {
                    return new PasswordAuthentication(username, password);
                }
            });

        try {
            Message message = new MimeMessage(session);
            message.setFrom(new InternetAddress(props_load.getProperty("setFrom")));
            message.setRecipients(Message.RecipientType.TO, InternetAddress.parse(sendto));
            message.setText("Some Text to be send in mail");
            Transport.send(message);
            result = "success";
        } catch (MessagingException e) {
            result = "fail";
            logger.error("Exception Occured - sendto: " + sendto, e);
        }
        return result;
    }
}