On Sun, 28 Nov 2010, der Mouse wrote:
Accepting mail only from IPv4 will be the norm and will not result
in any lost mail, even far into the future. Devices with only IPv6,
such as smart phones and desktops will send mail through smarthosts
with IPv4 connectivity.
Make up your mind: if a v6-only device smarthosts, the smarthost must
be accepting mail from v6.
Perhaps you meant accepting _arm's-length_ mail from v4 only? It's an
important distinction, in that it means, for example, that leaving v6
support entirely out of genera-purpose SMTP listener implementations
would be a Bad Thing.
Perhaps I should have said port 25, MSA traffic will of course come to the
MTA over v6 for domains that have v6 hosts originating messages.
I wouldn't disagree, even though steam comes from the ears of the
IETF old guard when one points this out.
I think I at least partially disagree.
If the big receivers (gmail, hotmail, mail.com, etc) don't take mail on
v6, spamware is unlikely to bother; if this happens, it means that
coming in over v6 correlates negatively with being spam, leading to a
spam advantage for accepting v6 mail for small receivers.
That isn't an equilibrium - the big receivers wouldn't maintain such a
policy if it increased their spam load.
Daniel Feenberg
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