Patent ID: 8417783

Claim:
A computer-implemented method for selecting spam features within a spam feature set comprising: processing program code in a processor to perform the operations of: providing a spam feature set comprised of a first subset of features configured to trigger upon receipt of spam email messages and a second subset of features configured to trigger upon receipt of valid email messages (“ham”), wherein the first subset of features comprise functions to identify spam email messages, and the second subset of features comprise functions to identify valid email messages; determining a first entropy value associated with the spam feature set, the first entropy value indicating how effectively the spam feature set differentiates between spam and ham; removing a feature from the spam feature set, the feature selected from either the first subset or the second subset; determining a second entropy value associated with the spam feature set without the feature, the second entropy value indicating how effectively the spam feature set differentiates between spam and ham after the feature has been removed; and if the second entropy value is less than the first entropy value, then discarding the feature from the spam feature set, and if the second entropy value is greater than the first entropy value, then retaining the feature in the spam feature set.