In <20050519053349(_dot_)2800754C8A(_at_)apex(_dot_)listbox(_dot_)com> Scott
Kitterman <spf2(_at_)kitterman(_dot_)com> writes:
[huge snip of how to score SPF results]
[SpamAssassin's scores are] a low fidelity reputation system where
each SPF result gets a collective reputation. IMO, the only things
SA should score on are Fail and Softfail.
I agree that SA shouldn't score None, Neutral or the error conditions,
but I *do* think it should score Pass in the following way: If a
result passes, you should *increase* the score given by the
auto-whitelist. Contrary to the auto-whitelist's name, this SA
feature is actually both a whitelist and a blacklist. If the SPF result
passes, then known ham sources will be whitelisted and you can be even
more certain that it isn't ham. Similarly, if the SPF result passes,
then known spam sources will be blacklisted and you can be even more
certain that it is spam.
-wayne