I was investigating a bunch of bitcoin spam: different titles, different senders (all from gmail), different text, different pdf attachment.
Unfortunately in those days my bayes db was polluted and they all got a BAYES_50, 0.8. I tested the messages now with a recreated bayes db and got some BAYES_999. So I dug to understand if I already saw the spam... But the debug result was unpleasant: dbg: bayes: tokenized header: 92 tokens dbg: bayes: token 'HX-Received:Jan' => 0.998028449502134 dbg: bayes: token 'HX-Google-DKIM-Signature:20210112' => 0.997244532803181 dbg: bayes: token 'H*r:sk:<START_OF_RECIPIENT_EMAIL_ADDRESS>' => 0.997244532803181 dbg: bayes: token 'H*r:a05' => 0.995425742574258 dbg: bayes: token 'HAuthentication-Results:sk:<MY_SA_HOSTNAME>.' => 0.986543689320388 dbg: bayes: token 'HX-Google-DKIM-Signature:reply-to' => 0.916110175863517 dbg: bayes: token 'H*r:2002' => 0.877842810325844 dbg: bayes: token 'HAuthentication-Results:2048-bit' => 0.858520043212023 dbg: bayes: token 'HAuthentication-Results:pass' => 0.855193895034317 dbg: bayes: score = 0.999997915091326 Every score is based on headers, very generic headers. and some related to my setup. Not a single token from the message body....