"Tony Finch" wrote:
I doubt that it makes sense to accept email from
test(_at_)ipv6(_dot_)l(_dot_)google(_dot_)com on a system that can only
communicate with IPv4 addresses.
In stark contrast to Ned's view I think that you
MUST reject such mails - unless you can guarantee
delivery without auto-response (no NDR, no DSN,
no MDN, no vacation, no forward, in essence an
empty reverse-path, near to rewrite MAIL FROM:<>)
Same idea as in EAI, after a reject "the sender
can make another plan". After accepting it the
IPv6-only mail vanished in a black hole for all
non-trivial cases.
Frank