Disclosed system and methods for detecting spam using shingles. In one aspect, the system receives an electronic message including at least a text portion. The system identifies in the received message insignificant text portions. The system then removes identified insignificant text portions to generate an abridged message. The system then generates a set of shingles from the abridged message. The system then indentifies in the generated set of shingles one or more shingles that occur only in messages not containing spam. The system then removes one or more identified shingles from the generated set of shingles to generate a reduced set of shingles. The system then performs spam filtering of the reduced set of shingles to determine whether the received message contains spam.