Sending E-mail with uploaded attachment

 protected void Btn_Send_Click(object sender, EventArgs e)
   {


       try
       {

           string to =Txt_To.Text;

           string[] str = to.Split(';');
           string from = Txt_From.Text;
           string from_pwd = "12345678";
           MailMessage mM = new MailMessage();
           mM.From = new MailAddress(from);

           foreach (string s in str)
           {
               mM.To.Add(s);
           }
         
           mM.Subject = Txt_Subject.Text;
           mM.Body = Txt_message.Text;
           mM.IsBodyHtml = true;

           string s1 = "";
          

           mM.Priority = MailPriority.High;
           SmtpClient sC = new SmtpClient("mail.kumbhaj.com");
           sC.UseDefaultCredentials = false;
           sC.Port = 25;

     
           if (FileUpload1.HasFile)
           {
               FileInfo f = new FileInfo(FileUpload1.FileName.ToString());
               s1 = Guid.NewGuid().ToString();
               s1 = "uploadfile/" + s1 + f.Extension;
               FileUpload1.SaveAs(Server.MapPath(s1));
               Attachment at = new Attachment(Server.MapPath(s1));
               mM.Attachments.Add(at);
           }

           sC.Credentials = new System.Net.NetworkCredential(from, from_pwd);
           sC.EnableSsl = false;
           sC.Send(mM);
           Lbl_Failled_Report.Text = "Message Successfully send.";
       }
       catch (Exception ex)
       {
           Lbl_Failled_Report.Text = "Message sending Failled!";
       }
   }