SMTP not getting connected

Here is my java code to send email, whenever i run the code it shows javax.mail.MessagingException: Could not connect to SMTP host: ipaddress, port: 25; I even tried changing the port number, still same error.. can anyone help me.. (i have included mail.jar and activation.jar to project)

public static void main(String arfs[]) throws UnknownHostException
{
    InetAddress address = InetAddress.getLocalHost(); 
                 String to="gggg@gmail.com";
                String from="vvvvv@gmail.com";
                String host=address.getHostAddress();

                Properties properties = System.getProperties();  
                properties.setProperty("mail.smtp.host",host);
                properties.setProperty("mail.smtp.port", "25");
                Session session = Session.getDefaultInstance(properties);  

                try{  
                     MimeMessage message = new MimeMessage(session);  
                     message.setFrom(new InternetAddress("vvvv@gmail.com"));  
                     message.addRecipient(Message.RecipientType.TO,new InternetAddress("ggggg@gmail.com"));  
                     message.setSubject("test email");  
                     message.setText("hello");  
                     Transport.send(message);  
                     System.out.println("message sent successfully....");  

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

        }

via Chebli Mohamed