It doesn't for me.
As to why. Unless I can understand how to get he filters working in Mail (which I have been unable to to as of yet) I wan to try something different.
You appear to be laboring under the misconception that you have to program
Mail's spam filter. You
train it, not program it. It ships in training mode by default. The messages shown in brown are those that
Mail's filter flagged as spam. If a flagged message is not spam, then select it and click
Not Junk. If an unflagged message is spam, then select it and click
Junk. In about two weeks depending on how many messages you receive,
Mail's spam filter will be sufficiently accurate that you may take it out of training mode. A
Junk Mail folder will appear in
Mail's sidebar. You may check the
Junk Mail folder from time to time to ensure that there are no false positives there. If a spam message gets through, then select it and click
Junk. It will be sent to the
Junk Mail folder.
Mail's spam filter will continue to learn from your manual selections.