It's not Bayesian, but it's pretty good: gnus. Problem is you have to
install the emacs text editor or variant (xemacs, etc), then learn
some of the rather obscure keystrokes. It's still very much keyboard
based rather than GUI/mouse.

gnus uses not kill files but score files:

All articles have a default score (`gnus-summary-default-score'),
which is 0 by default. This score may be raised or lowered either
interactively or by score files. Articles that have a score lower than
`gnus-summary-mark-below' are marked as read.

Gnus will read any "score files" that apply to the current group
before generating the summary buffer.

There are several commands in the summary buffer that insert score
entries based on the current article. You can, for instance, ask Gnus
to lower or increase the score of all articles with a certain subject.

There are two sorts of scoring entries: Permanent and temporary.
Temporary score entries are self-expiring entries. Any entries that are
temporary and have not been used for, say, a week, will be removed
silently to help keep the sizes of the score files down.

.. . . . .

7.6 Adaptive Scoring
====================

If all this scoring is getting you down, Gnus has a way of making it all
happen automatically--as if by magic. Or rather, as if by artificial
stupidity, to be precise.

When you read an article, or mark an article as read, or kill an
article, you leave marks behind. On exit from the group, Gnus can sniff
these marks and add score elements depending on what marks it finds.
You turn on this ability by setting `gnus-use-adaptive-scoring' to `t'
or `(line)'.

--
I did not know how to say goodbye. It was harder still, when I refused
to say it.
~ Native American saying