The E-Mail Frontier: Emerging Markets and Evolving Technologies by Daniel J. Blum and David M. Litwack. Addison-Wesley Publishing Company, Reading, MA: 1994. Publisher's description.
Blum and Litwack deliver a comprehensive and insightful treatment of electronic communication, at least as it stood at the end of 1994. The E-Mail Frontier stands as one of the best sources on the historical development, for relevant standards, and for technical information related to electronic communications.
The authors begin with a vision statement for electronic mail:
E-mail is a key communications application of the information age. It enables people or mail-enabled applications to exchange revisable multimedia information, workflow, and electronic data interchange transactions. This exchange can occur with anyone, anytime, anywhere with speed, ease of use, intelligence, security, and at low cost.
The book then proceeds to make its way through its major topics. The four broad categories include an overview, the market and the specific implementations that have emerged, the standards and technologies that underlie electronic communication, and finally a set of recommendations. While the market perspectives and specific e-mail implementations described in the book find themselves quickly dated, the treatments of the standards and technologies offer more lasting relevance. Chapters explore two parallel e-mail universes, that of the X.400 and X.500 based private networks and that of the SNMP-based Internet.
The authors give significant emphasis to X.400, devoting all of Chapter 6 to a technical treatment and parts of others to descriptions of X.400-based systems. I especially appreciated the straightforward explanations of the architecture and components that comprise an X.400 system: User Agent, Message Transfer Agent, Message Store, and Access Unit. Other issues such as security, integration with X.500 directory services, a nd interoperability with other messaging systems are also given significant attention.
Since the writing of this book, X.400 has lost considerable ground, while Internet Mail enjoyed explosive growth. Many considered Internet Mail as an intermediate solution while the world awaited the development and acceptance of X.400-based systems. Just as OSI never gained sufficient momentum to overcome the dominance of TCP/IP on the networking level, X.400 failed to gained supremacy over Internet Mail. Blum and Litwack give clear descriptions of the protocols and systems that comprise Internet Mail. Internet mail messages conform to a structure defined by RFC822. The mechanism for establishing standards related to the Internet involves "request for comments" or RFC's publicly submitted for review, and eventual acceptance and implementation. The Simple Mail Transfer Protocol (RFC 821) defines how messages transverse the Internet. Other Internet standards are integral to mail such as the Domain Name System. Privacy Enhanced Mail makes mail significantly more secure and Multipurpose Internet Mail Extensions allows the integration of non-textual information to mail interactions. While SMTP provides for the delivery of messages among mail servers on the Internet, other protocols structure the retrieval of mail by individual users from mail servers.
The Post Office Protocol (version 3) prevails as the preferred method for end-user retrieval of mail messages, especially through popular programs such as Eudora. While the book mentions the Interactive Mail Addressing Protocol, then in a version calle d IMAPbis2, it predates the recent explosion of IMAP version 4 implementations. IMAP holds significant architectural advantages over POP3, especially in the ability to provide access to mail from a variety of remote locations.
One of the major challenges to electronic messages involves directory services. E-mail works well and easily when participants already know each other's e-mail addresses. But for e-mail to become more effective, some means of discovering e-mail addresses must be available. While some alternatives have emerged such as Whois++, the directory services architecture with the most promise is X.500. Implementations of X.500-based directory services exist for both X.400 and Internet mail. One of the major complications relating to directory services involves how information on each local mail server can be shared and replicated among other servers. As the number of servers becomes large and the extent of the information expands, the ability to distribute and synchronize this information becomes enormously difficult. Even today, no authoritative e-mail directory service exists. Even the ability to have comprehensive directory services within large organizations continues to be difficult. Directory services continues to be a major obstacle in the achievement of electronic messaging conforming to Blum and Litwack's vision even today.
The business world takes electronic mail to a new dimension in support of financial transactions and electronic commerce. Electronic Data Interchange and X.12 provide one means of supporting these types of business activities. Many business have automat ed the process of purchasing, invoicing, and payment authorization through EDI, which defines a set of electronic conversations that can take place between businesses and customers in support of these transactions. The current business practices of just-in-time inventories would be difficult to maintain without the efficiencies offered by EDI over paper-based processes. An explosive development of electronic commerce has occurred since this book's writing. While EDI continues to be a mainstay of busine ss automation, many organizations have implemented models of electronic commerce based on the World Wide Web. The Web has become ubiquitous for many aspects of the commercial world and offers itself as a major vehicle for both consumer-oriented and business-to-business financial transactions.
Another dimension of E-mail emerges as electronic messaging becomes integrated into other applications and no longer exists only as a discrete activity. An increasing number of applications can automatically interact with other computer systems and with human participants through integrated electronic messaging capabilities. These types of "smart applications" will bring electronic messaging into the realm of workflow automation and will create opportunities for now ways of conducting business operations.
The book builds toward a concluding chapter that assesses the state of electronic messaging at the time of writing against the vision statement originally presented. The mixed results the authors described in 1994 persist through 1997. Successes include broad implementation of local, enterprise-wide, and global messaging systems, a rapidly increasing bandwidth of networks available for delivering messages, and a commercial world that makes considerable use of electronic commerce. Obstacles and remaining challenges involve security, manageability, and directory services.
Despite being a little dated, I consider The E-Mail Frontier a valuable resource for anyone needing to understand the underpinnings of electronic communication. While the approach of the book leans towards the technical, the material should be understandable to less technical readers also.