String to = "abc@example.com";
  String user = "sp@example.com";
  String pass = "1234";
    Properties props = new Properties();
    props.put("mail.smtp.host", "smtp.example.com");
    props.put("mail.smtp.port", "587");
    props.put("mail.smtp.auth", "true");
    props.put("mail.smtp.starttls.enable", "true");
Session session = Session.getInstance(props,new javax.mail.Authenticator()
{
  protected PasswordAuthentication getPasswordAuthentication()
  {
     return new PasswordAuthentication(user,pass);
  }
 });

session.setDebug(true);



 try
   {
    /* Create an instance of MimeMessage,
          it accept MIME types and headers
       */
    MimeMessage message = new MimeMessage(session);
       message.setFrom(new InternetAddress(user));
       message.addRecipient(Message.RecipientType.TO,new InternetAddress(to));
       message.setSubject(sub);
       message.setText(msg);
       /* Transport class is used to deliver the message to the recipients */
       Transport.send(message);
    }
    catch(Exception e)
    {
         e.printStackTrace();
    }