| The Email system makes people communicating with each other much easier than ever before, but it also brings a new problem to us - a great number of Spam mails. If an email fills in a personal mailbox without permission, it is a spam mail. Normally, spam mails are sent in a batch. Spam mails have wasted many network resource, disturbed personal communication, made the network unsafe. It is also used to spread virus or lawless information. Mail filtering cuts of the Spam mails and brings useful mails to the user.This paper describes a framework of anti-Spam based on postfix, the mail server and bridge-firewalling. The framework can send and receive mails, filter the spam mails on some basic rules, and more complex filtering method could be researched and practiced on it. User can transparently add a mail-filtering node behind the gateway, with out changing any network parameter. As a result of basing on Linux and postfix, the framework also has these features: security, stability, compatibility and extensibility. Cooperating with the console, it can also automatically identify the vicious user and update the blacklist and the rules in real time.Firstly, the paper gives an introduction to the background of the whole subject, and what to do in the subject. Secondly, it analyzes the requirement and makes general design, and brings forward the hardware and software framework. Thirdly, it describes how to implement the framework on a naked PC. Finally, it discusses on some key problems that may appear while implementing the framework, including how to solve them and some possible improvements. |
