There is a heuristic that says any host which is intended to act as a
server visible to hosts on the public Internet should have matching
forward and reverse DNS. (It does not say the converse; the presence
of DNS doesn't mean a host is good, the absence means it's bad.) This
seems to me to be perfectly relevant in IPv6.
Which at the current deployment levels, is only valid for IPv4, not
IPv6. Yet the anti-spammers have adopted it for IPv6.
I talk to a lot of people who run large mail systems at MAAWG, including
some of the largest ones in Canada. Their experience with the v6 mail
they send and receive is quite the opposite -- real mail hosts have real
DNS, whether on v4 or v6.
If your connection is over a consumer broadband network, your provider
probably considers it a feature that it's hard for you to send mail
without going through a relay with a static address and rDNS, not a bug.
Are you saying now that the IPv6 reverse checks should be dropped? I'm
confused.
No, I'm saying that hosts with static addresses that are intended to be
servers or mail clients should have DNS, for other hosts on random
addresses, there's no point. If you want your hosts to be visible to your
friends, you can use something like dyndns, and since they already know
you, the absence of rDNS shouldn't matter.
Regards,
John Levine, jo...@taugh.com, Taughannock Networks, Trumansburg NY
Please consider the environment before reading this e-mail.
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