java socket email 问题 - Java / Java SE

我在 java核心技术上 看了一个 利用 Java socket email的例子 可是怎么也 不成功 为什么？
源码
Java code:

package cn.com.test.email;

import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.InetAddress;
import java.net.Socket;
import java.util.Scanner;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;


public class MailTest {
public static void main(String[] args) {
JFrame frame = new MailTestFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
}

@SuppressWarnings("serial")
class MailTestFrame extends JFrame {
private Scanner in;
private PrintWriter out;
private JTextField from;
private JTextField to;
private JTextField smtpServer;
private JTextArea message;
private JTextArea comm;

public static final int DEFAULT_WIDTH = 300;
public static final int DEFAULT_HEIGHT = 300;

public MailTestFrame() {
setSize(DEFAULT_WIDTH,DEFAULT_HEIGHT);
setTitle(