Very few, but that's OK. Good spam fighters don't have to sacrifice many or really any toes to stop nearly all spam. You seem to be assuming a linear relationsh

Very few, but that's OK. Good spam fighters don't have to sacrifice many or really any toes to stop nearly all spam. You seem to be assuming a linear relationship between effort and false positives, but that would be a very ineffective spam fighting team relative to the ones I've worked on. In practice you can have nearly no false positives combined with nearly no false negatives. This isn't easy and many firms fail at it, but you it can be done and we routinely did it.