Sending an Email using gmail through Java

I am trying to send email through java using this code :

package send_email;
import java.util.Properties;  
import javax.mail.*;  
import javax.mail.internet.*;  
/**
 *
 * @author A
 */
public class Send_email {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        // TODO code application logic here
        String host="smtp.gmail.com";  
  final String user="***@gmail.com";//change accordingly  
  final String password="****";//change accordingly  

  String to="*******@gmail.com";//change accordingly  

   //Get the session object  
   Properties props = new Properties();  
   props.put("mail.smtp.host",host);  
   props.put("mail.smtp.auth", "true");  

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

   //Compose the message  
    try {  
     MimeMessage message = new MimeMessage(session);  
     message.setFrom(new InternetAddress(user));  
     message.addRecipient(Message.RecipientType.TO,new InternetAddress(to));  
     message.setSubject("javatpoint");  
     message.setText("This is simple program of sending email using JavaMail API");  

    //send the message  
     Transport.send(message);  

     System.out.println("message sent successfully...");  

     } catch (MessagingException e) {e.printStackTrace();} 
    }

}

But I get the following error :

javax.mail.MessagingException: Could not connect to SMTP host: smtp.gmail.com, port: 25, response: 554
    at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:1694)
    at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:525)
    at javax.mail.Service.connect(Service.java:313)
    at javax.mail.Service.connect(Service.java:172)
    at javax.mail.Service.connect(Service.java:121)
    at javax.mail.Transport.send0(Transport.java:190)
    at javax.mail.Transport.send(Transport.java:120)
    at send_email.Send_email.main(Send_email.java:48)
BUILD SUCCESSFUL (total time: 0 seconds)

I have allowed port 25 through firewall and then I have tested it using telnet " telnet smtp.gmail.com 25 " but I get this error 554 OutgoingFilter "You are temporarily deferred due to sending spam or virus pl ease contact 16333 for more information"

So how do I fix this error?