This section implies that publishing SPF -ALL is a risky move, which is
made worse by DMARC.   SPF -ALL is a only risk when (a) the message is
forwarded without MAILFROM rewrite and (b) the evaluator does not implement
DMARC.

Rather than telling senders to weaken their SPF policies, we need to make
it clear to evaluators that they should implement DMARC correctly.  Proposed
language for the second paragraph:

“By design, DMARC allows a verified and aligned DKIM signature to override
an unfavorable SPF result, including FAIL.    However, the full message,
including the DATA section, must be accepted before DMARC participation can
be determined and DKIM signatures can be evaluated.   Consequently, DMARC
evaluators SHOULD NOT use SPF results to reject a message prior to receipt
of the entire DATA section.”

When this was previously proposed, it was noted that some DMARC evaluators
consider the combination of SPF FAIL with a policy containing only "-ALL"
to be a special case which justifies early reject.  I think it is obvious
that if an evaluator does not wish to allow a DKIM override for that
situation, then the SHOULD NOT can be ignored.
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