Design And Implementation Of E-mail Filter System

With the wide application of E-mail, all kinds of junk mail or virus have invaded the E-mail system, serious impacting on it's common using. Currently, more filter systems implement themselves through adopting the setting of IP policy, researching the caption of E-mail, giving the limitation of the MIME format, or running the special algorithm involving in the intellective finding on the single computer. This scheme mainly adopts the way setting up the collecting center of junk or virus mail, collecting the data coming from the different computers, at the same time, gives the synthesis assess. If some new data has updated, the center notices the mail server for updating its database. Naturally, it can make the mail server discover the junk mail or virus mail. Meanwhile, it saves the network bandwidth and system resources and also improves the efficiency of mail filter.During its design, I use JAVAMAIL package for checking the junk words or junk mail address, etc. It can short the time for software tapping. Meanwhile, as JAVAMAIL is one subset of java language, naturally, I use java in designing my interface. Furthermore, because the form of virus or junk mail is changeable dynamically, one important factor is how to judge fast what it belong to. So, this system takes advantage of CORBA technique. Its main work is collecting the data coming from different clients and noticing mail server for updating the database of mail server.The filter system is based on the deep research in the e-mail system. This paper also analyses detailed how the system runs from high layer to low layer, including in the different protocol, service and interface. Meanwhile, it also uses some mail protocol such as SMTP, POP and IMAP. Furthermore, it need handle the mail format, involving in MIME protocol. How to distill some important information from mail is also one considerable side. In this way, JAVAMAIL expresses its value.During handling the mail accessories, one work is scanning virus and killing them if existed. It is implemented on the system by the key value of each virus. This way makes this work easy and simple, but when handling some transformed virus, it is very limited as it has a weak self-fitted capacity. Meanwhile, in order to scan virus in real time way, the virus database need dynamic update.