C# pop3 邮件接收程序

private void Connect_Click(object sender, System.EventArgs e)
        {
            //将光标置为等待状态
            Cursor cr = Cursor.Current;
            Cursor.Current = Cursors.WaitCursor;
            String a ,b,c; 
            //用110端口新建POP3服务器连接
            Server = new TcpClient(PopServer.Text, 110);
            Status.Items.Clear();

            try
            {
                //初始化
                NetStrm = Server.GetStream();
                RdStrm = new StreamReader(Server.GetStream());
                Status.Items.Add(RdStrm.ReadLine());

                //登录服务器过程
                Data = "USER " Username.Text CRLF;
                szData = System.Text.Encoding.ASCII.GetBytes(Data.ToCharArray());
                NetStrm.Write(szData, 0, szData.Length);
                Status.Items.Add(RdStrm.ReadLine());

                Data = "PASS " Password.Text CRLF;
                szData = System.Text.Encoding.ASCII.GetBytes(Data.ToCharArray());
                NetStrm.Write(szData, 0, szData.Length);
                Status.Items.Add(RdStrm.ReadLine());

                //向服务器发送STAT命令，从而取得邮箱的相关信息：邮件数量和大小
                Data = "STAT" CRLF;
                szData = System.Text.Encoding.ASCII.GetBytes(Data.ToCharArray());
                NetStrm.Write(szData, 0, szData.Length);
                //Status.Items.Add(RdStrm.ReadLine());

                //改变按钮的状态
                Connect.Enabled = false;
                Disconnect.Enabled = true;
                Retrieve.Enabled = true;

                //将光标置回原来状态
                Cursor.Current = cr;

            }
            catch (InvalidOperationException err)
            {
                Status.Items.Add("Error: " err.ToString());
            }
        }