It appears that Viktor Dukhovni <ietf-smtp(_at_)ietf(_dot_)org> said:
I take no issue with that. Just observing that whether it is MUST
or not is mostly moot, unless we're also deprecating 7-bit downgrade.
Interesting question. I presume there are still MTAs that can do downgrades
but how common is it in practice?
It breaks DKIM signatures unless the MTA can find the signing keys and resign
on the fly which seems a bit much.
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