The TCP/IP Guide  9  TCP/IP Application Layer Protocols, Services and Applications (OSI Layers 5, 6 and 7)       9  TCP/IP Key Applications and Application Protocols            9  TCP/IP File and Message Transfer Applications and Protocols (FTP, TFTP, Electronic Mail, USENET, HTTP/WWW, Gopher)                 9  TCP/IP Electronic Mail System: Concepts and Protocols (RFC 822, MIME, SMTP, POP3, IMAP)                      9  TCP/IP Electronic Mail Message Formats and Message Processing: RFC 822 and MIME

TCP/IP Electronic Mail Message Formats and Message Processing: RFC 822 and MIME 1 TCP/IP Electronic Mail RFC 822 Standard Message Format Overview, Structure and General Formatting Rules

One of the most astute observations I have read about internetworking applications is that their usefulness is proportional to the number of people who use them. TCP/IP e-mail is a great example: it is a powerful communication method in large part because almost everyone with a computer today participates in the system. The more people who sign on to use e-mail, the more powerful it becomes.

The creators of TCP/IP email realized that people who use the system would employ many different types of hardware and software. To ensure that everyone was able to understand all e-mail messages, regardless of who sent them, they specified a common message format for electronic mail messages. This format doesn't have an official fancy name; it is simply known by the name of the standard that defines it: the RFC 822 message format.

In this section I describe the RFC 822 message format, which forms the basis for electronic mail message transfer in TCP/IP. I begin with an overview of the format and the general structure of messages, and some of the overall rules used to format RFC 822 messages. I then describe the many headers used in RFC 822 e-mail messages, and how they are arranged into groups. I conclude with a brief look at how RFC 822 messages are processed and their contents interpreted.

TCP/IP Electronic Mail Message Formats and Message Processing: RFC 822 and MIME 1 TCP/IP Electronic Mail RFC 822 Standard Message Format Overview, Structure and General Formatting Rules