I found that some mails do not have any BAYES_* (e.g. BAYES_10, BAYES_80 etc) scores in the X-Spam-Status header field.
Is this a feature or a bug?
Feature. Bayes scores of exactly 50 are excluded from the rules. This generaly means the bayes engine is completely undecided about a given email.
And if it is a feature, can it be configured, so I always get it?
You could add another bayes rule to cover the small hole. Just be sure to give it an insignificant score.
Either that, or just realize that whenever BAYES_ is absent, it means the message scored dead-on 50/50 chance of being spam/nonspam.
