在vs3下调试无误的pop3收信程序

using System.Net.Sockets;
using System.Collections;
using System.IO;
using System.Net;
using System;
using System.Web.Mail;
public class POP3
{
    string POPServer;
    string user;
    string pwd;
    NetworkStream ns;
    StreamReader sr;
    public POP3(){}
    public POP3(string server, string _user, string _pwd)
    {
        POPServer = server;
        user = _user;
        pwd = _pwd;
    }
    private void Connect()
    {
        TcpClient sender = new TcpClient(POPServer,110);
        Byte[] outbytes;
        string input;
        try
        {
       ns = sender.GetStream();
       sr = new StreamReader(ns);
       sr.ReadLine();
       //Console.WriteLine(sr.ReadLine() );
       input = "user " + user + " ";