What file do I need to edit to change the score on ALL_TRUSTED?
In /etc/mail/spamassassin/local.cf (or similar):
score ALL_TRUSTED -1.0
But before you do that, make sure you are adjusting the score for the right reason. If you've got ALL_TRUSTED matching spam, make sure your trusted_networks is set correctly. If that's wrong, ALL_TRUSTED misfires will not be the only problem you have.
http://wiki.apache.org/spamassassin/TrustPath
