Stephane Bortzmeyer [bortzmeyer(_at_)nic(_dot_)fr] wrote:
But the syntax has a limitation: the header uses :
result = "Pass" / "Fail" / "TempError" / "SoftFail" /
"Neutral" / "None" / "PermError"
which are not SPF-specific terms. If you use SPF, not for
black-and-white filtering but for input to a bayesian decision
process, these words do not help.
You don't want to apply bayesian filtering to raw e-mail headers, or
spammers will start to put your MX name (batilda.nic.fr) (or similar
things to which context-supplying pre-/postfixes cannot be attached) into
their spam randomly which will denounce these valid bits of information in
your filter's view.
Use a bayesian filter that is aware of the syntax of the various headers,
or don't apply a bayesian filter to the headers at all.
I certainly would not want the "Received-SPF:" header syntax to be
extended with redundant result code prefixes such as "SPF-" just to
facilitate the gross abuse of bayesian filters. :-)