Study And Implementation Of Spam Filtering Technologies In E-mail Server

With the popularization of Internet, E-mail becomes one of the most convenient and economic communication methods. However, due to occupying large amount of transferring, storing and computing resources, spam not only greatly influences the common life of people, but causes many economic losses and security problems. According to the statistics, spam costs about 8$ to 10$ billion for the company all over the world to eliminate spam annually, and the cost will double every five month. So, the research of anti-spam technologies becomes one of the important tasks which will greatly affect the development of Internet.Currently the main method handling with spam is rules-based filtering. The disadvantages of this method are low accurate in checking and prone to inaccurancy, bad adaptation, bothering maintenance, incapability of blocking mails with virus, be short of the support for Chinese mail, etc. Aiming at the deficiency of the filter system against spam, how to increase the accuracy of filter system against spam how to decrease the inaccuracy against normal mails, how to improve the adaptation of filter system against spam, and the methods for scanning virus in mails are our main concerns in this thesis. And the solution of these problems is the key point in our research approach,These subjects are concentrated on the filtering against spam, further, design and implement a filter system against spam named SpamBlocker. The product integrates the inspection technology for filtering spam such as rules-filtering, Bayes classification, virus scanning and black/white list, etc. Furthermore, it adopts the rules of scoring to determine which mail is spam and the filtering rules to provide Bayes classification with sample for improvement. As a result, it improves the adaptation of the system for filtering the emerging spam. Via our test, the SpamBlocker is superior in anti-spam and it has been successfully applied in practice.The structure of this thesis is organized as follows: chapter one introduces the general status of spam, anti-spam technology and main concerns in this thesis; chapter two introduces several corresponding technology used in SpamBlocker; chapter three introduces the general design for SpamBlocker; chapter four and five respectively design and implement server and client of the MailFilter, focusing individual part...