My version is pretty similar to Jim's first two paragraphs.
2.7 Author Signature
An "author signature" is a Valid Signature where the domain of the
signing entity ("d=" value) is the same as the domain name in the Author
Address. This comparison is case insensitive.
For example, if a message has a Valid Signature with the DKIM-Signature
field containing "d=example.com" then example.com is asserting that it
takes responsibility for the message. If the message's From field
contains the address "b(_at_)sub(_dot_)example(_dot_)com", that would mean
that the
message does not have a valid Author Signature because the message is
not signed by the same domain.
Those are fine.
Informative Note: ADSP is incompatible with DKIM signing by parent
domains described in section 3.8 of [RFC4871] in which a signer uses
"i=" to assert that a parent domain is signing for a subdomain.
That's not fine, since we've just gone around and agreed that the
signing identity is d=. leave this paragraph out.
R's,
John
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