tailieunhanh - The Technical Development of Internet Email

The explosive development of networked electronic mail (email) has been one of the major technical and sociological developments of the past 40 years. A number of authors have already looked at the development of email from various The goal of this article is to explore a perspective that, surprisingly, has not been thoroughly examined: namely, how the details of the technology that implements email in the Internet have evolved. This is a detailed history of email’s plumbing. One might imagine, therefore, that it is only of interest to a plumber. It turns out, however, thatmuch of how email has evolved has depended on seemingly obscure decisions. Writing this article has been a reminder of how little. | The Technical Development of Internet Email Craig Partridge BBN Technologies Development and evolution of the technologies and standards for Internet email took more than 20 years and arguably is still under way. The protocols to move email between systems and the rules for formatting messages have evolved and been largely replaced at least once. This article traces that evolution with a focus on why things look as they do today. The explosive development of networked electronic mail email has been one of the major technical and sociological developments of the past 40 years. A number of authors have already looked at the development of email from various The goal of this article is to explore a perspective that surprisingly has not been thoroughly examined namely how the details of the technology that implements email in the Internet have evolved. This is a detailed history of email s plumbing. One might imagine therefore that it is only of interest to a plumber. It turns out however that much of how email has evolved has depended on seemingly obscure decisions. Writing this article has been a reminder of how little decisions have big consequences and I have sought to highlight those decisions in the narrative. Architecture of email In telling the story of how email came to look as it does today we start by describing in broad strokes today s world so that the steps in the evolution can be marked more clearly. Today s email system can be divided into two distinct subsystems. One subsystem the message handling system MHS is responsible for moving email messages from sending users to receiving users and is built on a set of servers called message transfer agents MTAs . The other subsystem which we will call the user agent UA works with the user to receive manage . delete archive or print and create email messages and interacts with the MHS to cause messages to be delivered. Readers may recognize this terminology as being roughly that developed by .