Blacklists Compared

18 August 2001

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Survey results for all known public IP-based DNS blacklists.

  Hits   DNS Zone
  5255  (total number of IP addresses tested, including 287 at SDSC)
   990  xbl.selwerd.cx
   954  (union of all zones except xbl.selwerd.cx)
   447  outputs.orbz.org
   287  inputs.orbz.org
   283  relays.ordb.org
   275  or.orbl.org
   181  blackholes.five-ten-sg.com (result 127.0.0.4 = unconfirmed opt-in)
   167  relays.mail-abuse.org
   140  relays.osirusoft.com (result 127.0.0.2 = relay)
   106  orbs.dorkslayers.com
    90  dev.null.dk
    84  blackholes.five-ten-sg.com (result 127.0.0.3 = dialup)
    55  spammers.v6net.org
    50* block.blars.org (new this week)
    47  blackholes.five-ten-sg.com (result 127.0.0.2 = spam source)
    37  blackholes.intersil.net (new this week)
    22  blocktest.relays.osirusoft.com (not a blacklist!)
    15  ztl.dorkslayers.com
    13  relays.osirusoft.com (result 127.0.0.3 = dialup)
     9  blackholes.mail-abuse.org
     9  dialups.mail-abuse.org
     3  relays.osirusoft.com (result 127.0.0.6 = spamware vendor)
     2  relays.osirusoft.com (result 127.0.0.4 = spam source)
     2  blackholes.five-ten-sg.com (result 127.0.0.5 = should be listed at MAPS)
     1  orbz.gst-group.co.uk (result 127.0.0.3 = relay)
     1  orbz.gst-group.co.uk (result 127.0.0.2 = relay output)

* A local routing problem at SDSC caused the DNS servers for
  block.blars.org to become unreachable part way through the
  lookups.  The number seen here is probably lower than it should be.
The web sites listed below provide detailed information about the DNS zones listed above, including their listing policies.

There is no known descriptive page for the list at xbl.selwerd.cx, where the listing policy is so aggressive that even its owner uses a whitelist to keep it from blocking wanted e-mail. Anyone contemplating the use of this zone to automatically block e-mail would be well advised to use a thorough whitelist of their own.
This document was last updated by Jeff Makey <jeff@sdsc.edu> on 19 August 2001.