1. A method for processing an electronic-mail message, comprising: receiving a message sent over a communication network, the message including a message body and received at an inbox of a mail device; receiving an indication from a user that the message is a junk message; and executing instructions stored in memory, wherein execution of the instructions by a processor: summarizes the message body to produce a summary, wherein summarizing the message body includes removing at least one word that is not useful in classifying the message, and replacing a word in the body of the message with an identifier that represents all synonyms of the word, generates a signature based on the summary, compares the generated signature to a database of signatures corresponding to signatures of previously received messages, and processes the message based on at least the generated signature.