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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 Access and Retrieval Protocols and Methods                           9  Other TCP/IP Electronic Mail Access and Retrieval Methods

TCP/IP Direct Server Electronic Mail Access 1 2 Usenet (Network News) and the TCP/IP Network News Transfer Protocol (NNTP)

I don't know about you, but I was pretty darned glad when bell bottoms went out of style… and then, rather mortified when they came back in style a few years ago! That's the way the world of fashion is, I suppose. And sometimes, even in networking, “what's old is new again”. In this case, I am referring to the use of the online TCP/IP e-mail access model.

Most e-mail users like the advantages of online access, especially the ability to read mail from a variety of different machines. What they don't care for is direct server access using protocols like Telnet (“Tel-what?”), UNIX (“my father used to use that I think…” J) and non-intuitive, character-based e-mail programs. They want online access but they want it to be simple and easy to use.

In the 1990s, the World Wide Web was developed and grew in popularity very rapidly, due in large part to its ease of use. Millions of people became accustomed to firing up a Web browser to perform a variety of different tasks, to the point where using the Web became almost “second nature”. It didn't take very long before someone figured out that using the Web would be a natural way of providing easy access to e-mail on a server. This is now sometimes called Webmail.

This technique is straight-forward: it exploits the flexibility of the Hypertext Transfer Protocol (HTTP) to informally “tunnel” e-mail from a mailbox server to the client. A Web browser (client) is opened and given a URL for a special Web server document that accesses the user's mailbox. The Web server reads information from the mailbox and sends it to the Web browser, where it is displayed to the user.

This method uses the online access model like direct server access, because requests must be sent to the Web server, and this requires the user to be online. The mail also remains on the server as when NFS or Telnet are used.

TCP/IP Direct Server Electronic Mail Access 1 2 Usenet (Network News) and the TCP/IP Network News Transfer Protocol (NNTP)