ISSN : 1796-217X
Volume : 3    Issue : 5    Date : May 2008

A Trust Based System for Enhanced Spam Filtering
Jimmy McGibney and Dmitri Botvich
Page(s): 55-64
Full Text:
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The effectiveness of current anti-spam systems is limited by the ability of spammers to adapt to
filtering techniques and the lack of incentive for mail servers to filter outgoing spam. A new
approach, based on decentralised trust management, is described in this paper. An architecture
and protocol, called TOPAS (Trust Overlay Protocol for Anti Spam), are presented. Each mail server
records trust measures relating to each other mail server of which it is aware. Trust by one mail
server in another is influenced by direct experience as well as recommendations issued by
collaborating mail servers. The TOPAS protocol specifies how these experiences and
recommendations are communicated between each spam filter and its associated trust manager,
and between trust managers of different mail servers. A technique for improving mail filtering
performance and the TOPAS protocol using these trust measures is also described. Finally,
experimental work is presented that illustrates use of the protocol in a simulated network scenario.
Initial results illustrate the dynamics of this system, and indicate the potential of this approach to
significantly improve rates of false positives and false negatives in anti-spam systems. This is an
extended version of a paper presented at the Availability, Reliability and Security Conference in April

Index Terms
trust management, trust protocols, spam filtering, e-mail security