Disclosed system and methods for detecting spam using shingles. An example system identifies in a received message one or more insignificant text portions based on a text pattern database storing defined insignificant text patterns not containing spam; removes at least a portion of the one or more identified insignificant text portions from the message to generate an abridged and canonized message; generates a set of shingles from the abridged and canonized message; identifies in the set of shingles one or more shingles based on a shingles database storing defined insignificant shingles that occur only in messages not containing spam; removes one or more identified shingles from the set of shingles to generate a reduced set of shingles upon detecting the one or more identified shingles matching at least one of the defined insignificant shingles; and determines whether the received message contains spam based on the reduced set of shingles.