This plugin implements the threshold-based auto-learning discriminator
for SpamAssassins Bayes subsystem. Auto-learning is a mechanism
whereby high-scoring mails (or low-scoring mails, for non-spam) are fed
into its learning systems without user intervention, during scanning.
Note that certain tests are ignored when determining whether a message
should be trained upon:
* rules with tflags set to learn (the Bayesian rules)
* rules with tflags set to userconf (user configuration)
* rules with tflags set to noautolearn
Also note that auto-learning occurs using scores from either scoreset 0
or 1, depending on what scoreset is used during message check. It is
likely that the message check and auto-learn scores will be different.