Patent ID: 8578484

Claim:
A method for identifying content in electronic messages, the method comprising: receiving an electronic message having been classified as spam; executing instructions stored in memory, wherein execution of the instructions by a processor: detects content included in the received electronic message, identifies metadata for the detected content, the metadata including a numerical signature comprising a concatenation of a plurality of numbers, each number characterizing an aspect of the content, generates at least one variation for the numerical signature, wherein the variation characterizes a plurality of aspects of content that is different from any content in the received electronic message, and generates a thumbprint based on the numerical signature and a thumbprint based on the at least one variation; and storing the thumbprints in a database in memory, the thumbprints being accessible from the database for comparison to a thumbprint of a subsequently received message, wherein the subsequently received message is classified as spam or not spam based on the comparison to the stored thumbprints.