Is it possible for bayes to add a negative score to a message?
Had a message passed to me that scored 4.1. The rules it hit on was one that adds 5.0 that I wrote and bayes_20. No other rules seemed to have hit on this particular message.
When I tried running the message through by hand it scored 6.1 but with bayes_99 that time. I think this was due to an sa-learn session having been run that morning so the bayes database was different on this run from when the message was received.
My assumption is that bayes can apply a negative score if the message matches ham it has learned in the past. Hopefully someone can confirm this or inform me how it really works.
Scoring wise bayes works like any other rule, it assigns the score given to it in 50_scores.cf.
Bayes scores under 50 generally indicate likelihood of nonspam, over 50 indicates likelihood of spam. The bayes probability score is based on your past training. How many SpamAssassin points that bayes probability gets is fixed:
grep BAYES_ /usr/share/spamassassin/50_scores.cf
score BAYES_00 0 0 -4.901 -4.900 score BAYES_01 0 0 -0.600 -1.524 score BAYES_10 0 0 -0.734 -0.908 score BAYES_20 0 0 -0.127 -1.428 score BAYES_30 0 0 -0.349 -0.904 score BAYES_40 0 0 -0.001 -0.001 score BAYES_44 0 0 -0.001 -0.001 score BAYES_50 0 0 0.001 0.001 score BAYES_56 0 0 0.001 0.001 score BAYES_60 0 0 1.789 1.592 score BAYES_70 0 0 2.142 2.255 score BAYES_80 0 0 2.442 1.657 score BAYES_90 0 0 2.454 2.101 score BAYES_99 0 0 5.400 5.400
As you can see, bayes can subtract up to 4.901 points, or add up to 5.400.
