public class EmailUtility {
public static void sendEmail(String host, String port, final String userName, final String password,
        String toAddress, String subject, String message) throws AddressException, MessagingException {

    // setting SMTP server properties
    Properties properties = new Properties();
    properties.put("mail.smtp.host", host);
    properties.put("mail.smtp.port", port);
    properties.put("mail.smtp.auth", "true");
    properties.put("mail.smtp.starttls.enable", "true");
    Session session = Session.getInstance(properties, new javax.mail.Authenticator() {
        protected PasswordAuthentication getPasswordAuthentication() {
            return new PasswordAuthentication(userName, password);
        }
    });
    // creates a new e-mail message
    Message msg = new MimeMessage(session);

    msg.setFrom(new InternetAddress(userName));
    InternetAddress[] toAddresses = { new InternetAddress(toAddress) };
    msg.setRecipients(Message.RecipientType.TO, toAddresses);
    msg.setSubject(subject);
    msg.setSentDate(new Date());
    msg.setText(message);

    // sending the e-mail
    Transport.send(msg);

}

<context-param>
    <param-name>host</param-name>
    <param-value>smtp.gmail.com</param-value>
</context-param>

<context-param>
    <param-name>port</param-name>
    <param-value>587</param-value>
</context-param>

<context-param>
    <param-name>user</param-name>
    <param-value>test.123@gmail.com</param-value>
</context-param>
<context-param>
    <param-name>pass</param-name>
    <param-value>12345698</param-value>
</context-param>

public void init() {
    // reading SMTP server setting from web.xml file
    ServletContext context = getServletContext();
    host = context.getInitParameter("host");
    port = context.getInitParameter("port");
    user = context.getInitParameter("user");
    pass = context.getInitParameter("pass");
}

protected void doPost(HttpServletRequest request,
        HttpServletResponse response) throws ServletException, IOException {
    // reading form fields
    String recipient = request.getParameter("recipient");
    String subject = request.getParameter("subject");
    String content = request.getParameter("content");
    System.out.println(recipient+" sub "+subject+" content "+content);

    String resultMessage = "";

    try {
        EmailUtility.sendEmail(host, port, user, pass, recipient, subject,
                content);
        resultMessage = "The e-mail was sent successfully";
    } catch (Exception ex) {
        ex.printStackTrace();
        resultMessage = "There were an error: " + ex.getMessage();
    }