probably not far off it, and to be honest, that's actually better than 99% of spam filtering that exists. I think it's more likely a "confidence" between 0-1,

probably not far off it, and to be honest, that's actually better than 99% of spam filtering that exists. I think it's more likely a "confidence" between 0-1, and then you can customise what is an acceptable threshold per account. Business accounts needing confidence 0.7 and free accounts needing confidence 0.6. That's how I'd think about it at least. Boolean is slightly too lossy.