1. A method for improving a statistical message classifier, the method comprising: receiving a message over a network communication interface; identifying by a processor executing instructions out of a memory a feature in the message that is associated with a junk count; testing the message with a machine classifier by the processor performing a calculation according to a logarithmic function including the junk count, wherein the machine classifier outputs a value for the statistical message classifier for storage in the memory; updating the statistical message classifier stored in the memory according to the logarithmic calculation made by the machine classifier, wherein the stored statistical message classifier corresponds to a probability that the feature in the message is spam; identifying that the message is spam based on the probability that the feature in the message is spam; and quarantining the message.
7. The method for improving a message classifier as recited in claim 1 , wherein the machine classifier includes a challenge-response classifier.