PTR records for IPv6

Lorenzo Colitti lorenzo at
Mon Sep 2 03:14:08 CEST 2013

On Mon, Sep 2, 2013 at 10:05 AM, Jason Fesler <jfesler at> wrote:

> On Sun, Sep 1, 2013 at 5:30 PM, Lorenzo Colitti <lorenzo at>
> wrote:
> > What's wrong with wildcard PTRs?
> >
> > *.e.f.a.c.8.b.d. IN PTR
> And, customer-café <> has AAAA
> records to what exactly?
> It isn't just reverse DNS.  It is reverse + matching forward DNS.
> Mismatches in the IPv4 world are greatly penalized both at SMTP time
> and by SpamAssassin.

To 2001:db8:cafe::. Then we can modify SMTP servers and spam systems to
look at only the first 64 bits and we sort of have parity to what we have

Of course, if people put multiple customers on the same /64 then those
customers can influence each other's reputations. But this is no different
to what happens today to customers on the same public IPv4 address (e.g.,
shared hosting, SMTP relay).
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