Based On Three-tier Network Equipment E-mail Filtering System

Email filter is a very important subject in network security. In order to solve the problem of email filter in a great of information, this paper main aimed at network layer of the OSI model. At the same time, many correlative technologies and correlative equipment's characteristic have been introduced in this paper.In the first part of the article, I enumerated several solutions to email filter,and analyzied their advantage" and disadvantage.Then email's characteristic has been presented in the paper.At last,I main introduced the copied netflow and the filtered netflow.