I have the scheduler to read files(CSV) and send mail to the Emails, which is found from that document.

I am using the Scheduler with gmail's/our's smtp on local machine made no issues, while sending mail even with wrong "To:" mail id.
but in hosting when scheduler send mail to wrong mail id,  scheduler stops at smtp.Send(mail)  and Error caught. 

public override void DoWork()
{
      try
         {
              try
              {
                       this.Progressing();
                       string[] files = System.IO.Directory.GetFiles(System.Web.Hosting.HostingEnvironment.MapPath("/NewCSVContactFiles"));
                       foreach (string filePath in files)
                        {
                             DataTable dt = ConvertCSVFileToDataTable(filePath)
                             sendMails(dt);
                        }
                 }
                 catch (Exception ex)
                 {
                        this.ScheduleHistoryItem.AddLogNote(" : " + ex.InnerException.ToString());
                        //Catch: HERE
                 }
                 this.ScheduleHistoryItem.Succeeded = true;
         }
        catch (Exception ex)

        {
                //--intimate the schedule mechanism to write log note in schedule history
                this.ScheduleHistoryItem.Succeeded = false;
                this.ScheduleHistoryItem.AddLogNote("FileProcessSchedule Start. Failed. " + ex.InnerException.ToString());
                this.Errored(ref ex);
        }
}

public sendMails(Datatable dt)
{
      try
         {
                foreach (DataRow row in dt.Rows)
                 {
                       SendEmail(from,password,to,subj,content);
                 }
         }
        catch (Exception ex)
        {
                //Catch: sendMails
        }
}


public SendEmail(string From,string Password,string ToMail,string Sub,string Content)
{
      try
         {
                MailMessage mail = new MailMessage();
                MailAddress fromMail = new MailAddress(From);
                mail.From = fromMail;
                mail.To.Add(ToMail);
                SmtpClient client = new SmtpClient("smtpout.xxx.net");
                client.DeliveryMethod = SmtpDeliveryMethod.Network;
                client.UseDefaultCredentials = false;
                client.Port = 25;
                client.Host = "smtpout.xxx.net";
                client.EnableSsl = false;
                mail.Subject = strSubject;
                mail.Body = strBody;
                mail.IsBodyHtml = true;
                client.Credentials = new System.Net.NetworkCredential(strFrom, Pass);
                client.Send(mail);                //Stops here but not catch by Catch: SendMails its catch by Catch: HERE and shows null refrence at sendMails(dt)
                                                     Only this happened, when To address is not existing (eg: karthikeyanmlp123789@gmail.com (not registered but valid mail format))
         }

        catch (Exception ex)
        {
                //Catch: SendMails
        }
}

Note: I am not use throw inside any catch