Protocols for Addressing the Envelope Correctly: Internet Message Formats

Protocols for Addressing the Envelope Correctly: Internet Message Formats

When an e-mail client sends an e-mail and the e-mail servers forward it, they not only send the text of the e-mail message, but also a header. The header contains several fields, including the recipient's and sender's e-mail addresses, as shown in Figure 8-5.

RFC 2822, "Internet Message Formats," defines the, well, uh, format of Internet e-mail messages. Yes, the name is a bit self-defining. RFC 2822 defines the header fields shown in Figure 8-5, and many more, so that all the clients and servers know where to find all the information needed to forward the e-mail correctly.