[ipv6-wg] I thought e-mail over IPv6 was easy

> I saw the headline for this article and thought, "wtf, e-mail just
> worked over IPv6 from the time I put the AAAA record in the DNS". But I
> went ahead and had a look, and it is actually pretty interesting:
> http://engineering.linkedin.com/email/sending-and-receiving-emails-over-ipv6

Actually, it's even more complicated than that.

I need to send mail directly instead of "use the provider relay" because
the provider relay doesn't allow me to check whether mail is still queued - 
not all the world has reliable mail delivery, unfortunately and for
the people I work with, this is an issue.

For IPv4, it's easy for an ISP to set up stub forward & reverse records
and that's what I got away with for many, many years.

For IPv6, the situation is different. As discussed, users have more than
one address and hence may need need more than one forward/reverse pair,
and the address may not be predictable.  This gives new problems:
* If the connection is big enough to warrant delegation, then making
  FCrDNS work for IPv6 is doable.
  For small businesses and home power users however, this may not be
  feasible. 
* Making forward & reverse match for every /48 of every customer is
  a challenge;
* Delegating may not be feasible. 
  How do you delegate to "John's pet animal and sushi shop"? 
  The guy probably doesn't run a DNS server to delegate to..
* Making Dynamic DNS updates work between ISP and customer is a challenge
  at best;
* I have not seen any portal solutions, to let the customer handle this.
  Even with XS4all, for whom I am a customer, doesn't have an 
  automated way for this and the current workaround involves manual 
  intervention with all it's nasty scaling properties.
* I don't think that customer-specific subdomains and SPF-records will
  scale either.

I don't hear much of this new, IPv6-specific problem. Comments?

Geert Jan