rfc821简单邮件传输(smtp)协议详解，编写收发邮件程序必备 -rfc821 Simple Mail Transfer (smtp) explain the agreement, the preparation of the necessary procedures to send and receive e-mail

一个通讯行业的规范性文档，详细讲述了如何实现smtp的规范，了解之后，任何编程语言都能实现发送邮件服务-A normative document communications industry, smtp detail how to implement the specification, understand, any programming language can send e-mail services to achieve