Nobody with any experience or knowledge about email would seriously
suggest blocking mail solely due to lack of an SPF record or a
SenderID record or a DK or DKIM signature or an S/MIME signature or an
X-Herring: Red header.
Why is that?
It's not my contention that it could be done in practice, just that the
ongoing "discussion" about a "new email paradigm" based on pricing
email, email postage, etc. as a IETF standard to thwart spam might have
more than a technical consideration to its implementation (which doesn't
mean a programming language, but how you'd get millions of server and
billions of users to cooperate and adopt it worldwide).
David
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