smart_route: 
  driver = manualroute 
  domains = ! +local_domains 
  ignore_target_hosts = 127.0.0.0/8 
  condition = "${perl{check_limits}}"
  #use auth_relay if you do need to set the remote smtpauth 
  transport = auth_relay
  route_list = * smtp.zoho.com::587 
  no_more