Show only specific columns and hide others when sending ASP.Net GridView in Email Body

Check this

protected void Button1_Click(object sender, EventArgs e)
    {
        fn_AttachGrid(); //  here calling function to send mail gridview data as excel format
    }
    public void fn_AttachGrid()
    {
        try
        {
           
   
                StringWriter stw = new StringWriter();
  
                HtmlTextWriter hw = new HtmlTextWriter(stw);
  
                //Hide Columns
                foreach(GridViewRow row in GridView1.Rows)
                {
                         //Hide first column
                        row.Cells[0].Visible = false;
                }
                GridView1.RenderControl(hw);
  
  
                MailMessage mail = new MailMessage();
  
                mail.IsBodyHtml = true;
  
                mail.To.Add(new MailAddress("rafi045@gmail.com"));
  
                mail.Subject = "Sales Report";
  
                System.Text.Encoding Enc = System.Text.Encoding.ASCII;
  
                byte[] mBArray = Enc.GetBytes(stw.ToString());
  
                System.IO.MemoryStream mAtt = new System.IO.MemoryStream(mBArray, false);
  
                mail.Attachments.Add(new Attachment(mAtt, "sales.xls"));
  
                mail.Body = "Order Form" + txtname.Text + "," + txtemail.Text + "," + txtaddress.Text;
  
                SmtpClient smtp = new SmtpClient();
  
                mail.From = new MailAddress("rafi045@gmail.com", "Your Name");
  
                smtp.Host = "smtp.gmail.com";
                smtp.Port = 587;
  
                smtp.UseDefaultCredentials = false;
  
                smtp.Credentials = new System.Net.NetworkCredential(@"rafi045@gmail.com", "pwd");
  
                smtp.EnableSsl = true;
  
                smtp.Send(mail);
                lblerror.Text = "your order Sent to admin panel. We will contact you soon";
            }
        }
        catch (Exception ex)
        {
              
            lblerror.Text = ex.Message;
        }
  
    }