Markku Savela wrote:
The goal should be to make IPv4 and IPv6 easily replaceable anywhere,
whithout any reduced functionality.
I don't see how requiring MX lookups for IPv6 mail relaying reduces
functionality. As far as I can tell, it increases functionality because
it provides (as a side effect) an easy, low-overhead way to say "this
domain doesn't accept mail" in an IPv6 world. Just don't list any MX or
A records for it.
I guess the case that isn't being given much attention is the one where
you have an IPv6 address assigned to a host, and you have a domain name
associated with that address, and you want that host to be able to
receive mail - but you don't have write permission for the DNS RRs for
that domain, so you can't create MX records for it. But to me the
solution to that is easy - get your own domain name.
(IMHO the idea that some other party besides the one that runs a host
should be able to make assertions in DNS about that host's domain name
has always been fairly broken - we have ended up with a tussle between
DNS administrators and host owners/administrators as a result.)
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