Study And Implementation Of Spam Filtering System Based On The Client Side

Email is becoming the most popular, convenient and economic means of communication, due to its cheapness and the popularization of internet. However, at the same time, When users receive their own messages, they are also annoyed by the various ads from network, the flooding of all kinds of Spam has become a headache problem for human and society. Therefore, an effective, smart and flexible spam filtering technology is indispensable.After analyzing the principle of Email system,the SMTP protocol and the feature of E-mail format in Unix/Linux system, this thesis points out the bugs of SMTP protocol and introduces the methods of tracing the source of Spam. On the basis of research in the Anti-Spam technology, the author put forward a project of Spam filtering by combining the methods on the basis of the the Client Side. Filtering technologies that combine a improved blacklist and whitelist technology and technology which is based on CCERT rules are employed in the muti-layers Filtering system, By introducing the novel users' feedback mechanism, the system can adapt requirement of specific users to fulfill spam filtering. And the technique is able to reduce false positives and improve the veracity and availability of anti-spam system.Attacks to content-based E-mail filter, an Improved algorithm for Chinese String Matching is provided, and improve the availability of anti-spam system.