Abstract: In response to the spam problem, the present mail transfer protocol-SMTP was analyzed. As the commands are transmitted by plaintext in the SMTP, it is easy to bring forth some hidden trouble of safety. So the SMTP was extended in its type of data and credibility. Based on the result, a new model was set up and its realization was tested. The result of test shows that the case is effective.

Key words: Spam, SMTP protocol, Analyzing protocol, Extending protocol

摘要： 针对目前垃圾邮件问题，对现有的邮件传输协议——SMTP协议进行分析，由于SMTP协议规定的命令是以明文方式进行的,容易带来一些安全隐患。所以,对其进行一定的扩展,扩展了邮件发送数据类型和信息的可信度。根据扩展后的协议建立了新的模型，对其实现并加以测试。测试结果表明该方案有效。

关键词: 垃圾邮件, SMTP协议, 协议分析, 协议扩展 