import java.io.*; 
 import java.net.*; 
 public class Pop3test 
 {
    public static void main(String[] args)
    {
     try{
     Socket s = new Socket(args[0],110);
     BufferedReader in  = new BufferedReader(new InputStreamReader(s.getInputStream())); 
        BufferedWriter out = new BufferedWriter(new OutputStreamWriter(s.getOutputStream())); 
        String str;
        str = in.readLine();
        System.out.println("初始化结果"+str);
        
        out.write("USER wxyxln");
        out.flush();
        str = in.readLine();
        System.out.println("用户名输入结果 "+str);
        
        out.write("pass wxyxl78n");
        out.flush();
        str = in.readLine();
        System.out.println("密码输入结果 "+str);
        
        out.write("listn");
        out.flush();
        str = in.readLine();
        System.out.println("List "+str);
        
        int i=0;
        while((str = in.readLine()) != null) 
        { 
           System.out.println(str);
           if (!(str.equals("."))) 
             { 
              i++; 
             } 
           else
              break;           
        } 
        
        System.out.println("共有 "+i+" 封邮件");
        
        String result = "";
        byte[] b;
        for (int j=1;j'9'?ch1-'A'+10:ch1-'0')*16+
(ch2>'9'?ch2-'A'+10:ch2-'0');
putchar(hz);
}
else putchar(ch);
}
fclose(fp);
}

email里明明有这么一行：
Content-Transfer-Encoding: quoted-printable

编码方式就是quoted-printable，一个等号后面跟ASCII码，就这么简单。