Once SpamAssassin has been trained with enough spam and ham emails, it will begin to apply the Bayesian test automatically, if it is enabled. However, not every email will receive a Bayesian score. The Bayesian subsystem only gives a probability if it can make an authoritative estimate. To do this, it needs to recognize words (more correctly tokens) that it has seen in previous ham or spam emails. One way to confirm the operation of the Bayesian filter is to examine the headers of emails that have been processed by SpamAssassin and search for the result of a
BAYES_ test. The
X-Spam-Status header in an email may look like this:
X-Spam-Status: No, hits=3.5 required=4.0 tests=BAYES_50,DATE_IN_PAST_03_06, RCVD_IN_RFCI,RCVD_IN_SBL ...