The percentage of hamThe percentage of ham messages that are later reported as spam is what is used to generate the classification performance that can be seen on the main page. This fluctuates around 99.7% currently. Ham messages marked as spam cannot be detected because Mollom does not allow administrators to mark content as ham (to prevent obvious abuse), but the Mollom backend is set-up such that this will never happen. A message is only marked as spam if the text based classification is very confident that it is spam, and if the poster's internal reputation is very poor, meaning that he has already been posting spammy content for quite a while. So this is a two stage process that makes sure the humans will not get blocked. In an upcoming blog post I will elaborate some more on this reputation aspect.