public class MailSender {

    private final String username = "адрес ящика, с которого отправляем письмо";
    private final String password = "пароль к почтовому ящику";

    public  void MailSending(Message DataMessage){

        Properties props = new Properties();
        props.put("mail.smtp.starttls.enable", "true");
        props.put("mail.smtp.auth", "true");
        props.put("mail.smtp.host", "smtp.gmail.com");
        props.put("mail.smtp.port", "587");
        props.put("mail.smtp.ssl.trust", "smtp.gmail.com");


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

        try {
            MimeMessage message = new MimeMessage(session);
            message.setFrom(new InternetAddress(DataMessage.getFrom()));
            message.addRecipient(MimeMessage.RecipientType.TO, new InternetAddress(DataMessage.getTo()));
            message.setSubject(DataMessage.getSubject());
            message.setText(DataMessage.getBody());

            Transport.send(message); System.out.println("Email Sent successfully....");
        } catch (MessagingException mex){ mex.printStackTrace(); }

    }