1. A method for processing electronic messages (e-mails) is provided, the method comprising: receiving an electronic message, wherein the received electronic message includes a sender's address; comparing the sender's address associated with the electronic message to sender addresses found on a blacklist that contains a plurality of sender addresses and signatures of previously sent spam; executing instructions stored in memory, wherein the instructions are executed by a processor to: receive user input that classifies the received electronic message when the sender's address for the received electronic message is not found within the blacklist, and update the blacklist based on the received user input, wherein updating the blacklist comprises: summarizing content of the received electronic message, wherein summarizing the content of the received electronic message includes identifying that the content includes at least one word that has a plurality of possible canonical equivalents, selecting one of the equivalents for the at least one word based on likely association with the spam, assigning a probability of occurrence to the at least one word in the received electronic message, and the probability of occurrence corresponding to a probability that the at least one word occurs in a language, generating one or more signatures for the received electronic message based on the summarized content, and associating the generated signatures with the sender's address, and process the received electronic message based on the blacklist and based on the selected equivalent most likely being associated with the spam.