On Jan 2, 2020, at 5:33 PM, John Levine <johnl(_at_)taugh(_dot_)com> wrote:
If a host doesn't get v4 connections, it doesn't need to recognize v4
address literals. Similarly, if it doesn't get v6 connections it
doesn't need to recognize v6 literals.
Emphatically disagree, because of NATs. It’s counterproductive to gratuitously
impair smtp to prevent it from being used across ipv4/IPv6 boundaries, across
boundaries between public and private ipv4 networks, and across boundaries
between private ipv4 networks. It’s also counterproductive to put something
into a specification that implementors have to ignore for pragmatic reasons.
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