How can i check Authentication on gmail?

Question

Well i want to check if the data put by the user is a correct gmail account.I do this by sending to them a confirmation e-mail.If the email is not sent then an AuthenticationFailedException is thrown. But when i put the correct ones it continues to throw the Exception. Furthermore, if i put the correct data from the beginning and change them afterwards it continues to send the confirmation email even though the new data are false. I use the code above. I assume that it holds on to the Session first created.But how do i create a new session everytime?

public class GmailSender extends javax.mail.Authenticator {
private String mailhost = "smtp.gmail.com";
private String user;
private String password;
private Session session;

public GmailSender(String user, String password) {
    this.user = user;
    this.password = password;

    Properties props = new Properties();
    props.setProperty("mail.transport.protocol", "smtp");
    props.setProperty("mail.host", mailhost);
    props.put("mail.smtp.auth", "true");
    props.put("mail.smtp.port", "465");
    props.put("mail.smtp.socketFactory.port", "465");
    props.put("mail.smtp.socketFactory.class","javax.net.ssl.SSLSocketFactory");
    props.put("mail.smtp.socketFactory.fallback", "false");
    props.setProperty("mail.smtp.quitwait", "false");

    session = Session.getDefaultInstance(props, this);

}

protected PasswordAuthentication getPasswordAuthentication() {

    return new PasswordAuthentication(user, password);
}   


public synchronized void sendMail(String subject, String body, String sender, String recipients) throws Exception {

    MimeMessage message = new MimeMessage(session);
    DataHandler handler = new DataHandler(new ByteArrayDataSource(body.getBytes(), "text/plain"));
    message.setSender(new InternetAddress(sender));
    message.setSubject(subject);
    message.setDataHandler(handler);
    if (recipients.indexOf(',') > 0)
        message.setRecipients(Message.RecipientType.TO, InternetAddress.parse(recipients));
    else
        message.setRecipient(Message.RecipientType.TO, new InternetAddress(recipients));
    Transport.send(message);
}

public class ByteArrayDataSource implements DataSource {
    private byte[] data;
    private String type;

    public ByteArrayDataSource(byte[] data, String type)    {
        super();
        this.data = data;
        this.type = type;
                                                            }

    public ByteArrayDataSource(byte[] data) {
        super();
        this.data = data;
                                            }

    public void setType(String type)    {
        this.type = type;
                                        }

    public String getContentType() {
        if (type == null)
            return "application/octet-stream";
        else
            return type;
                                    }

    public InputStream getInputStream() throws IOException  {
        return new ByteArrayInputStream(data);
                                                            }

    public String getName() {
        return "ByteArrayDataSource";
                            }

    public OutputStream getOutputStream() throws IOException    {
        throw new IOException("Not Supported");
                                                                }

}

}

Answer 1

Insted of session = Session.getDefaultInstance(props, this);

use session = Session.getInstance(props, this);

you will be fine!!

Answer 2

you missing the authentication part you need to set the userid and password to authentication in properties object.

props.put("mail.smtp.user", userid);
props.put("mail.smtp.password", password); 

checkout this blog for complete example http://www.techlabs4u.com/2010/08/java-code-to-send-email-using-java-mail.html