Need to make Javamail more secure for gmail authentication

Question

I have written a code for sending a simple mail from java(javamail/jaf). after I run the program I got an email from google that my account is being accessed by unsecured device/app. Then I had to change the settings of my gmail account to allow login for "less secure apps" option. Then I received my email from the program.

I need to send email without changing the option allow "less secure apps" option in my account. Please help.

My code is:

import java.util.Properties;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;

public class SendMailSSL {
    public static void main(String[] args) {
        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.port", "465");

        Session session = Session.getDefaultInstance(props,
            new javax.mail.Authenticator() {
                protected PasswordAuthentication getPasswordAuthentication() {
                    return new PasswordAuthentication("*****@gmail.com","*******");
                }
            });

        try {

            Message message = new MimeMessage(session);
            message.setFrom(new InternetAddress("*****@gmail.com"));
            message.setRecipients(Message.RecipientType.TO,
                    InternetAddress.parse("*****@gmail.com"));
            message.setSubject("Testing Subject");
            message.setText("Dear User," +
                    "\n\n No spam to my email, please!");

            Transport.send(message);

            System.out.println("Done");

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

Answer 1

The only way to avoid this for Gmail is to use OAuth 2.0 authentication. You can read about it through this link. https://developers.google.com/gmail/xoauth2_protocol?hl=en