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Block IPv6-only at the border (was: I-D Action:draft-klensin-rfc2821bis-10.txt)

2008-04-16 12:14:47

"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