[Exim] dumping mail for non-users on hubbed host

i have a hubbed host with only three legit users, but it
receives a few hundred thousand dictionary and other
smtp slop per day. is there a nicer way than the
following to sink bogus mail on my main inbound mail
host?

    # send to victim hubbed host for legit users
    route_hubbed_user:
      driver = manualroute
      domains = hubbed.my.dom.ain
      route_list = hubbed.my.dom.ain $domain byname
      local_parts=user0:user1:user2
      transport = remote_smtp

    # kill for all other address on victim hubbed host
    hubbed_kill:
      driver = manualroute
      domains = hubbed.my.dom.ain
      route_list = hubbed.my.dom.ain $domain byname
      transport = kill

    # send to all other hubbed hosts
    hubbed_hosts:
      driver = manualroute
      domains = ! +local_domains
      route_list = hubbed.my.dom.ain $domain byname
      transport = remote_smtp

randy