Unable to connect to the remote server C#

public void SendMaiL(string sSubject, string[] arToAddress, string[] arToAddressCC, int? iReqEmpId, int iMailType)
  {
      string sBody = string.Empty;
      bool enableSSL = true;

      if (arToAddress != null && arToAddress.Length > 0)
      {
          try
          {
              string sServer = "smtp.mail.com";
              int iPort =587;
              string sUserName = ConfigurationManager.AppSettings["userName"].ToString();
              string sPassword = ConfigurationManager.AppSettings["password"].ToString();
              string sFrom = ConfigurationManager.AppSettings["from"].ToString();

              //oSmtpClient.UseDefaultCredentials = false;
              //oSmtpClient.Credentials = new NetworkCredential(sUserName, sPassword);

              MailMessage oMailMessage = new MailMessage(); ;
              oMailMessage.From = new MailAddress(sFrom);
              if (arToAddress != null && arToAddress.Length > 0)
              {
                  sBody = GetMailBody(Convert.ToInt32(arToAddress[0]), iMailType, iReqEmpId);
                  for (int t = 0; t <= arToAddress.Length - 1; t++)
                  {
                      oMailMessage.To.Add(new MailAddress(GetEmpMailId(Convert.ToInt32(arToAddress[t].ToString()))));
                  }
              }
              if (arToAddressCC != null && arToAddressCC.Length > 0)
              {
                  for (int i = 0; i <= arToAddressCC.Length - 1; i++)
                  {
                      if (arToAddressCC[i] != null)
                          oMailMessage.CC.Add(new MailAddress(GetEmpMailId(Convert.ToInt32(arToAddressCC[i].ToString()))));
                  }
              }
              oMailMessage.Subject = sSubject;
              oMailMessage.Body = sBody;
              oMailMessage.IsBodyHtml = true;

              using (SmtpClient smtp = new SmtpClient(sServer, iPort))
              {
                  smtp.Credentials = new NetworkCredential(sFrom, sPassword);
                  smtp.EnableSsl = enableSSL;
                  smtp.Send(oMailMessage);
              }

          }
          catch (Exception ex)
          {
              //WriteLog(ex.ToString());
          }
      }
  }