Email.java

import java.io.UnsupportedEncodingException;
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.AddressException;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;

public class Email {

    public static void main(String[] args) {
        
        String username = "your email";
        String password = "your password";

        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");

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

        try {
            Message message = new MimeMessage(session);
            message.setFrom(new InternetAddress(username));
            message.setRecipients(Message.RecipientType.TO,
                InternetAddress.parse("recipient email..."));
            message.setSubject("Activation Email");
            message.setText("The Activation Link");
            Transport.send(message);
            System.out.println("Message Sent Successfully!");
        } catch (MessagingException e) {
            throw new RuntimeException(e);
        }
    }
}