This is from a message I receive every day from a Yahoo Groups spam, which I never signed up for and have been unsuccessfully able to remove myself from. It's always from the same address, and the message is always formatted the same way, so it seems it would be an easy task for the learning mechanism to recognize it. I have flagged it as spam every day for at least 2 months now, but as you can see from the header it still shows a Bayesian probability of 0. At this point I've completely lost faith in the "Spam" button. Or am I misunderstanding what it's supposed to do?
X-Spam-Status: No, score=-4.897 tagged_above=-10 required=6.6
tests=[AM:BOOST=-3, BAYES_00=-1.9, DKIM_ADSP_CUSTOM_MED=0.001,
DKIM_SIGNED=0.1, DKIM_VALID=-0.1, FREEMAIL_FROM=0.001,
T_RP_MATCHES_RCVD=-0.01, T_TO_NO_BRKTS_FREEMAIL=0.01] autolearn=ham