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Re: [anti-spam-wg] Domains with MX set to localhost

  • To: der Mouse mouse@localhost
  • From: Jan Pieter Cornet johnpc@localhost
  • Date: Wed, 11 Jan 2006 17:14:25 +0100

On Wed, Jan 11, 2006 at 10:50:38AM -0500, der Mouse wrote:
> >> [...blocking certain spammer domains...]
> > We block a domain if:
> > . the MX host is "." (following draft-delany-nullmx)
> > . the MX host isn't a FQDN
> > . the MX host has no associated A record at all
> > . the A record of the MX record is localhost, RFC1918, link-local,
> >   class D/E, or a limited set of bogons (yes, I'm watching IANA
> >   allocations)
> How is the second one possible?  An MX record isn't capable of
> containing anything *but* a FQDN.  (Or does this really mean "MX hosts
> in nonexistent top-level domains"?)

Sorry, my mistake. I meant if the sender domain is not a FQDN.
Which happens frequently enough from badly configured host to warrant
a specific error message.
> As for the third one - do you actually mean "address record", or do you
> specifically not want to talk to people with IPv6-only MX hosts?  Or do
> you block only when *all* MX hosts are problematic? 

We certainly only block when all MX records are problematic, but I
oversimplified it heavily. We also check for AAAA records and accept
the email if it finds one (even though our mailservers currently don't
speak IPv6).

#!perl -wpl # mmfppfmpmmpp mmpffm pmmppfmfpppppfmmmf@localhost
$_[2]}->(map{/p|f/i+/f/i}split//,$&)+97):qw(m p f)[map{((ord$&)%32-1)/$_%3}(9,
3,1)]),5,1)='`'lt$&;$f.eig;                                # Jan-Pieter Cornet