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Table Of Contents  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

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TCP/IP Direct Server Electronic Mail Access
(Page 1 of 2)

In my overview discussion of e-mail message communication, I discussed the different devices involved in a complete mail exchange, and how a message is created and then transported from the originator to the recipient. SMTP is used to carry the message most of the way, to the recipient's mailbox. The last step of the process is to convey the message from the server where the mailbox is located to the machine the client is using.

This final portion of the e-mail journey is usually the job of an e-mail access and retrieval protocol like POP3 or IMAP4. These are customized protocols, by which I mean that they were created specifically for the last step of the e-mail communication process. However, there are also several generic methods by which an e-mail client can gain access to a mailbox, without the use of a special protocol at all.

E-Mail Direct Access Methods

These methods are all variations of the online e-mail access model. They generally work by establishing direct access to the server where the mailbox is located. The mailbox itself is just a file on a server somewhere, so if that file can be made available, it can be viewed and manipulated like any other file using an e-mail client program that reads and writes the mailbox file. The following are some of the ways in which this can be done:

  • Using The SMTP Server Directly: Obviously, the simplest method for gaining access to the mailbox is to simply log on to the server itself. This is not an option for most people, and even in years gone by it was not often done, for security reasons as well as others. However, even today there are some people who do run their own SMTP servers, giving them considerable control over access to their e-mail.

  • File Sharing Access: Using a protocol such as the Network File System, it is possible to have a mailbox mounted on a user's client machine where it can be accessed as if it were a local file. The mail is still on the server and not the client machine, but the communication between the client and the server occurs “transparently” to both the user and the e-mail client software.

  • Dial-Up Remote Server Access: A user on a client machine dials up a server where his or her mailbox is located and logs in to it. The user then can issue commands to access mail on that server as if he or she were logged in to it directly.

  • Telnet Remote Server Access: Instead of dialing in to the server, a user can connect to it for remote access using the Telnet Protocol.

Previous Topic/Section
Other TCP/IP Electronic Mail Access and Retrieval Methods
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TCP/IP World Wide Web Electronic Mail Access
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Version 3.0 - Version Date: September 20, 2005

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