System.Net.Mail.Tests.SmtpServer.Dispatch C# (CSharp) Method

        private bool Dispatch(NetworkStream ns, StreamReader r, string s)
        {
            Trace("command", s);
            if (s.Length < 4)
            {
                WriteNS(ns, "502 Unrecognized\r\n");
                return false;
            }

            bool retval = true;
            switch (s.Substring(0, 4))
            {
                case "HELO":
                    break;
                case "EHLO":
                    WriteNS(ns, "250-localhost Hello" + s.Substring(5, s.Length - 5) + "\r\n");
                    WriteNS(ns, "250-AUTH PLAIN\r\n");
                    break;
                case "QUIT":
                    WriteNS(ns, "221 Quit\r\n");
                    return false;
                case "MAIL":
                    _mailfrom = s.Substring(10);
                    break;
                case "RCPT":
                    _mailto = s.Substring(8);
                    break;
                case "DATA":
                    WriteNS(ns, "354 Continue\r\n");
                    while ((s = r.ReadLine()) != null)
                    {
                        if (s == ".")
                            break;

                        if (s.StartsWith("Subject:"))
                        {
                            _subject = s.Substring(9, s.Length - 9);
                        }
                        else if (s == "" && _body == null)
                        {
                            _body = r.ReadLine();
                        }
                    }
                    Trace("end of data", s);
                    retval = (s != null);
                    break;
                default:
                    WriteNS(ns, "502 Unrecognized\r\n");
                    return true;
            }

            WriteNS(ns, "250 OK\r\n");
            return retval;
        }