IronPortC-Series邮件安全网关技术建议书IronPortSystems2007年1月目录1.简介.........................................................................................................................................32.垃圾邮件的现状.....................................................................................................................52.1什么是垃圾邮件.............................................................................................................53.目前的几种反垃圾邮件技术.................................................................................................64.传统技术的缺陷.....................................................................................................................75.IronPort安全邮件网关的技术特点.......................................................................................85.1专用的MTA平台AsyncOS™.......................................................................................85.1.1无堆栈线程.............................................................................................................85.1.2输入输出调度机制.................................................................................................95.1.3AsyncFS文件系统.................................................................................................95.1.4防邮件攻击...........................................................................................................105.1.5DomainKeys技术.................................................................................................115.1.6BounceVerification退信校验..............................................................................125.2反垃圾功能(Anti-Spam)...............................................................................................135.2.1SenderBase名誉得分过滤技术...........................................................................135.2.2深层内容过滤技术...............................................................................................145.2.3基于上下文分析的扫描引擎（CASE）.............................................................145.2.4图片垃圾邮件过滤技术.......................................................................................145.3邮件通道控制...............................................................................................................155.4邮件流量监控...............................................................................................................155.5高性能...........................................................................................................................165.6别名功能.......................................................................................................................165.7防病毒技术...................................................................................................................165.8VOF主动式病毒预防技术..........................................................................................166.系统介绍...............................................................................................................................166.1网络结构.......................................................................................................................176.2工作原理.............................................
