string postData = "t=qf_booked_feedback&id=3ef0963350a0570a66a32f2d3dbffc75c190b23cc7690702&to=999999999@qq.com";
            //验证码
            string verifycode_cn = txtVal.Text.Trim();    
            //如果输入了验证码
            postData += verifycode_cn.Length > 0 ? "&verifycode_cn=" + verifycode_cn : "";

            ASCIIEncoding encoding=new ASCIIEncoding(); 
            byte[] data = encoding.GetBytes(postData);   
              
            // Prepare web request...   
            HttpWebRequest myRequest = (HttpWebRequest)WebRequest.Create("http://list.qq.com/cgi-bin/qf_compose_send");   
            
            ///测试代码
            //CookieContainer mc = new CookieContainer();
            //myRequest.CookieContainer = mc;
            ///测试结束
            
            myRequest.Method = "POST";   
            myRequest.ContentType="application/x-www-form-urlencoded";   
            myRequest.ContentLength = data.Length;  
            Stream newStream=myRequest.GetRequestStream();   
              
            // Send the data.   
            newStream.Write(data,0,data.Length);   
            newStream.Close();
              
            // Get response   
            HttpWebResponse myResponse=(HttpWebResponse)myRequest.GetResponse();

            StreamReader reader = new StreamReader(myResponse.GetResponseStream(), Encoding.GetEncoding("utf-8"));   
            string content = reader.ReadToEnd();
            reader.Close();

            //测试用代码，查看结果
            this.richTextBox1.AppendText(content);
            this.webBrowser1.DocumentText = content;