Standards and Protocols
Given the number and diversity of the mail systems and computer types that communicate with each other across the Internet, the formulation and adoption of standards is vital. The primary vehicle for the definition of such standards is the RFC or Request for Comments. As its name suggest, the idea behind an RFC is that someone writes up a proposed solution to a problem, publishes the proposal and requests comments on it. After a period of time, if the proposal is successful it is accepted as a standard solution. Full details of all Requests for Comments and their current status can be found at: http://ds.internic.net/ds/rfc-index.html.
One of the most important of these standards as far as Internet Mail is concerned is the Simple Mail Transfer Protocol.