sa-exim and whiltelists

I've read through the archives regarding user based preferences and
understand the arguments against it.  I've also seen the various sorcery one
could use to make it work by using Tom Kistner's strategy.  My question is
slightly different since I'm only interested in whitelists.  What I'd like
to do is one of two things.  Either not scan a message if ANY of the
recipients have whitelisted the sender, or, adjust the score so that it
would not be considered spam.  The whitelists would be stored in a mysql
database.  I found a post in the spamassassin-talk archive
(http://marc.theaimsgroup.com/?l=spamassassin-talk&m=105567290926230&w=2)tha
t states that this could be done using the exclusion rule.  What are your
thoughts on the best way to do this?

Thanks,

Nick