How to solve authentication required while sending mail using ASP.NET C#

In Asp.net c#   i have  created a web app which sends mail to desired destination  and this thing works from localhost ,my live project is  uploaded on solidcp panel and from that  live website my mail sending function does not work.I also allowed less secure apps from gmail settings but still not working.
Is there something i should configure from solidcp panel or my code needs some changes?

public void SendMail(string strTO, string strSubject, string strBody, FileUpload objFileUpload = null)
  {
      try
      {

          tblSettings objSettings = new tblSettings();
          objSettings.LoadAll();

          if (objSettings.RowCount > 0)
          {
              string strFrom = objSettings.AppSiteEmail;
              //"rahul.b4r097@gmail.com""sanikp@keyconcepts.co.in";
              if (strTO == "")
              {
                  strTO = objSettings.AppRecepientEmail;
              }
              MailMessage mail = new MailMessage(strFrom, strTO, strSubject, strBody);
              mail.IsBodyHtml = true;


              SmtpClient smtp = new SmtpClient();
              smtp.Host = objSettings.AppSMTP;
              //"smtp.gmail.com"

              if (!string.IsNullOrEmpty(objSettings.s_AppPortNumber))
              {
                  smtp.Port = Convert.ToInt32(objSettings.AppPortNumber.ToString());
                  //587
              }

              smtp.UseDefaultCredentials = false;
              smtp.Timeout = 60000;

              clsEncryption objEncrypt = new clsEncryption();

              smtp.Credentials = new System.Net.NetworkCredential(strFrom, objEncrypt.Decrypt(objSettings.AppEmailPassword, appFunctions.strKey));
              if (objSettings.s_AppIsSSL != "")
              {

                  smtp.EnableSsl = Convert.ToBoolean(objSettings.AppIsSSL);
              }
              else
              {
                  smtp.EnableSsl = false;
              }
              var str = objEncrypt.Decrypt(objSettings.AppEmailPassword, appFunctions.strKey.ToString());
              string exe = " MailTO: " + strTO + " ,MailFrom: " + strFrom + " ,Subject :" + strSubject +  " ,Host: " + smtp.Host + " ,Port: " + smtp.Port + " ,SSL: " + smtp.EnableSsl+ ",appSiteEmail: "+ objSettings.AppSiteEmail+ " ,appRecipientEmail "+ objSettings.AppRecepientEmail +  " ,Password: "+str ;
              LogError(exe);
              smtp.DeliveryMethod = SmtpDeliveryMethod.Network;


              smtp.Send(mail);

              LogError(strTO);

              smtp = null;
              mail = null;
          }
      }
      catch (Exception ex)
      {
          string message = string.Format("Time: {0}", DateTime.Now.ToString("dd/MM/yyyy hh:mm:ss tt"));
          message += Environment.NewLine;
          message += "-----------------------------------------------------------";
          message += Environment.NewLine;
          message += string.Format("Message: {0}", ex.Message);
          message += Environment.NewLine;
          message += string.Format("StackTrace: {0}", ex.StackTrace);
          message += Environment.NewLine;
          message += string.Format("Source: {0}", ex.Source);
          message += Environment.NewLine;
          message += string.Format("TargetSite: {0}", ex.TargetSite.ToString());
          message += Environment.NewLine;
          message += "-----------------------------------------------------------";
          message += Environment.NewLine;
          string path = HttpContext.Current.Server.MapPath("~/Error/ErrorLog1.txt");
          // Check if file already exists. If yes, delete it.
          if (!File.Exists(path))
          {
              File.Delete(path);
              var myFile = File.Create(path);
              myFile.Close();
              System.IO.File.WriteAllText(path, message);

              myFile.Close();
              return;

          }


          if (File.Exists(path))
          {
              File.Delete(path);
              var myFile = File.Create(path);
              myFile.Close();
              System.IO.File.WriteAllText(path, message);

              myFile.Close();
              return;
          }










      }

  }