We can define a specification for us by others because all evaluators face
a similar threat profile.   Anyone who has worked the problem, or can
reasonably imagine himself working the problem, should be able to draw
similar conclusions.

We cannot talk about how to specify Failure Reporting until we understand
the process of which it will be a part, and that process analysis begins
with use cases.   I see four:

   1. The From address is accurate.  The sender and his message are also
   acceptable.
   2. The From address is accurate.  The sender and his message are
   unacceptable.
   3. The From address is fraudulent.  The From domain is a secondary
   victim of the attack.
   4. The From address is fraudulent.   The From domain is also controlled
   by the attacker.

The first and most obvious conclusion is that for use cases #2 and #4,
nothing good can come from sending a a Failure Report.  Reporting can only
serve to help the attacker perfect his attack.

For use case #1, the goal of a failure report is to help the Domain Owner
correct problems that are within his control, or to make him aware that I
am working around problems that he cannot correct because they are
downstream from his control.

For use case #3, the goal of a failure report is to cooperate with the
Domain Owner to find ways to minimize the harm that the attacker can cause.

If failure reporting does occur, we are imposing on the report sender an
obligation to perform record keeping to distinguish between repeat
occurrences and to minimize excessive duplication.  We need to at least
think how we would define the reporting strategy for these two cases if we
were creating our own implementation.   The current specification does some
hand waving on this topic because we have not thought it through.

Finally, these use cases create a problem for the recurring fiction that
DMARC can produce correct results on a fully automated basis without
exerting any human effort to collect additional information.   Our document
needs to move away from ficion.

Doug Foster
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