It would be useful for Mail Transfer Agents (MTAs) <strike>implementing
message acceptance restrictions </strike> to be able to confirm that
information provided by peer MTAs' is consistent with a description
of the configuration of the purported origin.
There's any number of possible uses for the information. Need it be limited
to one kind of use? (so if Phillip can't bring himself to say 'policy' we
shouldn't say anything narrower). Consider an MTA that just labels the
message ... leaving accept/deny to another entity.