[Spambayes] Any ideas about this one?

[Tim Peters]

[T. Alexander Popiel]
> It probably was in the midrange zone to be ignored (.4 to .6 by
> default).

[Skip Montanaro]
> The default is 0.5 (meaning show everything):
> ...
>     clue_mailheader_cutoff: 0.5

I expect Alex had this mind:

# When scoring a message, ignore all words with
# abs(word.spamprob - 0.5) < minimum_prob_strength.
# This may be a hack, but it has proved to reduce error rates in many
# tests.  0.1 appeared to work well across all corpora.
minimum_prob_strength: 0.1

abs(p-0.5) < 0.1  is-same-as  0.4 < p < 0.6; Classifier._getclues() doesn't
return any word with a spamprob in that range.