i created one .doc file from c# and sending in mail , its opening in pc but not opening in mobile

try
      {
          if (Session["Projectname"] != null && Session["Projectname"].ToString() != string.Empty)
          {

              string Projname = Session["Projectname"].ToString();
              System.IO.StringWriter stringWrite = new System.IO.StringWriter();
              System.Web.UI.HtmlTextWriter htmlWrite = new HtmlTextWriter(stringWrite);

              design.RenderControl(htmlWrite);

              string strBuilder = stringWrite.ToString();
              string strPath = Request.PhysicalApplicationPath + "\\Temp\\WeeklyReport of " + Projname + ".docx";

              LblNoteMsg.Text = strPath;
              if (File.Exists(strPath))
              {
                  var counter = 1;
                  strPath = strPath.Replace(".docx", " (" + counter + ").docx");
                  while (File.Exists(strPath))
                  {
                      strPath = strPath.Replace("(" + counter + ").docx", "(" + (counter + 1) + ").docx");
                      counter++;
                  }
              }
              using (var fStream = File.Create(strPath))
              {
                   fStream.Close();
                   fStream.Dispose();

              }
               using(StreamWriter sWriter = new StreamWriter(strPath))
                 {
              sWriter.Write(strBuilder);
              sWriter.Close();
              sWriter.Dispose();
              Response.Clear();
                 }
              DateTime input = DateTime.Now;
              int delta = DayOfWeek.Monday - input.DayOfWeek;
              DateTime dats = DateTime.Now.AddDays(delta);
              //this week
              DateTime monday = input.AddDays(delta);
              string MonDate = monday.ToShortDateString();
              DateTime sat = monday.AddDays(5);
              string SatDate = sat.ToShortDateString();
              StreamReader r = new StreamReader(Server.MapPath("~/WeeklyMail.txt"));
              string body = r.ReadToEnd();
              MailMessage Msg = new MailMessage();
              string MailId = txtMailId.Text;
              foreach (string ss in MailId.Split(",".ToCharArray()))
              {
                  if (string.IsNullOrEmpty(ss) == false)
                  {
                      Msg.To.Add(new MailAddress(ss));
                  }
              }
              Msg.Bcc.Add(new MailAddress("support@sunlightit.com"));
              body = body.Replace("<%MonDate%>", MonDate);
              body = body.Replace("<%SatDate%>", SatDate);
              Msg.Subject = "Weekly status Report of " + Projname + "," + DateTime.Now.ToShortDateString() + "";
              Msg.Body = body;
              Msg.IsBodyHtml = true;
              Msg.Attachments.Add(new Attachment(strPath));
              SmtpClient MailServer = new SmtpClient();
              try
              {
                  MailServer.Send(Msg);
                  string reply = (Msg.DeliveryNotificationOptions = System.Net.Mail.DeliveryNotificationOptions.OnSuccess).ToString();

                  if (reply == "OnSuccess")
                  {
                      txtMailId.Text = "";
                      tblMail.Visible = false;
                      lblMsg.ForeColor = System.Drawing.Color.Green;
                      lblMsg.Text = "Mail has send succesfully";
                  }
                  else
                  {
                      lblMsg.ForeColor = System.Drawing.Color.Red;
                      lblMsg.Text = "Mail delivery unsuccessfull";
                  }

              }