关于发送邮件问题

以下程序在往163.com的邮箱发邮件时，报 Exception in thread "main" java.net.UnknownHostException: mailhost。
请大侠看看问题

public class SendMail {
	public static void main(String[] args) throws IOException {
//		if (args.length == 1)
//			System.getProperties().put("mail.host", args[0]);
		
		Properties props = System.getProperties();
		props.put("mail.smtp.host", "smtp.163.com");
		props.put("mail.smtp.port", "110");
		props.put("mail.smtp.auth", "true");
		
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		
		System.out.print("From: ");
		String from = in.readLine();
		System.out.print("To: ");
		String to = in.readLine();
		System.out.print("Subject: ");
		String subject = in.readLine();
		
		URL url = new URL("mailto:" + to);
		URLConnection c = url.openConnection();
		c.setDoInput(false);
		c.setDoOutput(true);
		c.connect();
		System.out.println("Connecting......");
		PrintWriter out = new PrintWriter(c.getOutputStream());
		
		out.print("From: \"" + from + "\" <" + System.getProperty("user.name") + "@" + 
		           InetAddress.getLocalHost().getHostName() + ">\r\n");
		out.print("To: " + to + "\r\n");
		out.print("Subject: " + subject + "\r\n");
		out.print("\r\n");
		
		System.out.println("Enter the mail message. End with a '.' on a line by itself.");
		String line;
		for(;;) {
			line = in.readLine();
			if (line == null || line.equals(".")) break;
			out.print(line);
		}
		
		out.close();
		in.close();
	}
}