I have the same version of spamassassin running on two different Slackware computer. I believe I have enabled the Bayesian classifier on both. One host does give me Bayes scores in the message header, for example:
* 0.0 HTML_MESSAGE BODY: HTML included in message
* 2.0 BAYES_50 BODY: Bayes spam probability is 40 to 60%
* [score: 0.5000]
The other host's spamassassin never does. I'm quite sure the recalcitrant host has been trained with plenty of spam and ham.
Any ideas why Bayes in not kicking in on this host? What can I check?