SMTPセッションフィルタとグレイリストを併用した迷惑メール対策

A Measure of Using SMTP Session Filtering and Greylisting to Counter Spam Mail

Abstract
In this paper, we analyzed the feature of the virus and illegitimate mail header. The analysis results show that the difference between the legitimate and illegitimate mails (say spam mail) is evident. Based on the analysis results, we elaborately designed a mail SMTP session filtering and a greylisting scheme to counter virus and spam mails. The scheme is expressed concretely as several rules. We implemented the rules with Postfix at mail server side. The experiment results show that the countermeasure we have presented is quite powerful, and the virus mail of 97% and spam mail of 91% have been rejected without receiving the contents of the mail.