On 08/17/2012 05:02 PM, Paul Smith wrote:
On 17/08/2012 22:08, Daniel Feenberg wrote:
On Fri, 17 Aug 2012, Michael Thomas wrote:
On 08/17/2012 01:51 PM, Daniel Feenberg wrote:
Host operating systems -- all of them to my knowledge -- prefer v6 over v4 if
you have a public v6 address. So the mere existence of a AAAA associated with
the MX will cause the sender to pick the v6 destination. I have a v6 mail
system and got bitten because I had forgot to put up the v6 reverse map. It
will happen just as a natural consequence of people enabling v6 on their
infrastructure.
This sounds inconvenient. If I want to accept mail from one IPv6 host, then all the IPv6 hosts will want to use IPv6, and unless I accept mail from unknown IPv6 hosts, mail from hosts that would have been accepted over IPv4 will be rejected?
This is a fair point. Given that IPv6 is rare at the moment and is really an
'extension' to SMTP anyway, maybe we should be looking at a further extension
which allows an SMTP receiver to say 'retry on my IPv4 address'
Seriously, let's not go here. Any such extension would be DOA in the IETF
anyway.
If DNSBL's are the reason you would want to stay in v4 land, I'd suggest
the problem is with the way DNSBL's are engineered, not v6. Thislist being
an IETF research group should just accept that v6 will arrive and not try
to roll back time.
Mike
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