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;
//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;
//将光标置回原来的状态
Cursor.Current = cr;
}
catch(InvalidOperationException err)
{
Status.Items.Add("Error: "+err.ToString());
}
}