Re: dual-stack IP transition is not specific to SMTP

> Basically, the current task is one of supporting a dual-stack networking 
> environment.  That's a challenge for all Internet use, not just email. 
> Solutions for it need to be universal, not specific to email.
Doesn't follow.  Different applications use the network in different 
ways, and IPv6 doesn't impact all applications in the same way.  IPv6 is 
not a drop-in replacement for IPv4, and there is no one-size-fits-all 
solution to adapt applications to IPv6.
> The SMTP specification should be modified in the smallest and most 
> localized fashion possible and particularly should not make any changes 
> to its registration model.
Again, it doesn't follow.  Yes, small and localized changes are 
generally to be preferred over elaborate changes that don't add any 
functionality.  But eliminating AAAA fallback is a small and localized 
change - and it has the added benefit of making mail simpler and more 
robust.
Keith