Sending email via GMail with Java SE environment

GMailSender.java

package br.com.otavio.mail.helper;

import java.util.Properties;

import javax.mail.Authenticator;
import javax.mail.Message;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;

/**
 * Sends an e-mail using GMail,

 * @author Otávio S Garcia
 */
public class GMailSender {

	private static final String SMTP_HOST = "smtp.gmail.com";
	private static final int SMTP_PORT = 465;

	private final String user;
	private final String pass;

	private boolean debug;

	public GMailSender(String user, String pass) {
		this.user = user;
		this.pass = pass;
	}

	/**
	 * All transport messages will printed into console.
	 */
	public GMailSender debug() {
		debug = true;
		return this;
	}

	/**
	 * Sends the email.
	 */
	public void sendMail(String from, String to, String subject, String message) {
		final Session session = Session.getDefaultInstance(createMailProperties(), createAuthenticator());
		final Message msg = new MimeMessage(session);

		try {
			msg.setRecipient(Message.RecipientType.TO, new InternetAddress(to));
			msg.setFrom(new InternetAddress(from));
			msg.setSubject(subject);
			msg.setContent(message, "text/plain");

			msg.saveChanges();

			Transport.send(msg);
		} catch (Exception e) {
			throw new IllegalStateException("The e-mail can't sent.", e);
		}
	}

	private Authenticator createAuthenticator() {
		return new GMailAuthenticator(user, pass);
	}

	private Properties createMailProperties() {
		final Properties props = new Properties();

		props.put("mail.transport.protocol", "smtp");
		props.put("mail.smtp.starttls.enable", "true");
		props.put("mail.smtp.host", SMTP_HOST);
		props.put("mail.smtp.auth", "true");
		props.put("mail.smtp.user", user);
		props.put("mail.smtp.port", SMTP_PORT);
		props.put("mail.smtp.socketFactory.port", SMTP_PORT);
		props.put("mail.smtp.socketFactory.class", "javax.net.ssl.SSLSocketFactory");
		props.put("mail.smtp.socketFactory.fallback", "false");
		props.put("mail.debug", String.valueOf(debug));

		return props;
	}

	class GMailAuthenticator extends Authenticator {
		public final String username;
		public final String password;

		public GMailAuthenticator(String username, String password) {
			this.username = username;
			this.password = password;
		}

		@Override
		protected PasswordAuthentication getPasswordAuthentication() {
			return new PasswordAuthentication(username, password);
		}
	}
}