Simple Mail Client

Question

I try to create simple mail client. Now I can receive list of messages from mail box:

        // create an instance of TcpClient
        TcpClient tcpclient = new TcpClient();
        // HOST NAME POP SERVER and gmail uses port number 995 for POP 
        tcpclient.Connect("pop.gmail.com", 995);
        // This is Secure Stream // opened the connection between client and POP Server
        System.Net.Security.SslStream sslstream = new SslStream(tcpclient.GetStream());
        // authenticate as client  
        sslstream.AuthenticateAsClient("pop.gmail.com");
        //bool flag = sslstream.IsAuthenticated;   // check flag
        // Asssigned the writer to stream 
        StreamWriter sw = new StreamWriter(sslstream);
        // Assigned reader to stream
        StreamReader reader = new StreamReader(sslstream);
        // refer POP rfc command, there very few around 6-9 command
        sw.Write("USER my_login@gmail.com\r\n");
        // sent to server
        sw.Flush();
        sw.Write("PASS my_pass\r\n");
        sw.Flush();

        // this will retrive your first email
        sw.Write("LIST\r\n");
        sw.Flush();

        // close the connection
        sw.WriteLine("QUIT\r\n");
        sw.Flush();

        richTextBox2.Text = reader.ReadToEnd();

        sw.Close();
        reader.Close();
        tcpclient.Close();

I don't uderstand why it is possible to read from stream only after sending command QUIT? If I try to read stream to end or all lines from stream before sending message QUIT my program crashes. Can anyone help me?

Thank you very much!

Answer 1

Your program doesn't crash, it hangs. It hangs because ReadToEnd() waits for an EOF which doesn't get sent by the server until the connection is closed.