1. An information processing system comprising: at least one router configured for: routing an email message from a sender node to a destination node; and adding information to the email message, said information comprising delivery path information of the email from the sender node to the destination node; a system memory; a network interface for receiving the email message, said email message comprising a plurality of packets and delivery path information; a database for storing a plurality of prior delivery paths from previously analyzed emails; a processor configured for: extracting the delivery path information from the email message; determining a network path for the email message using the delivery path information; comparing the delivery path information with the plurality of prior delivery paths; determining a measure of similarity between the network path of the received email message and one or more of the plurality of prior email paths; and determining a spam score for the email received, based on the measure of similarity.