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.) Keith _______________________________________________ IETF mailing list IETF@xxxxxxxx https://www.ietf.org/mailman/listinfo/ietf