Command-Line Emailby Robert Bernier
When my editor asked me to write an article on email, my first reaction was to mimic a sound I used to hear on Sesame Street. Come on now; what can be written about email that hasn't already been said? What can children and grandparents both do at the drop of a hat? What easier way is there to share a joke or comment on the latest goings-on? What more efficient and flexible monitoring and report tool does there exist for the system administrator?
However, back in my early years I was confused to no end by all those terms that I had to know stone cold. Obscure combinations of letters and numbers had to be memorized. There's so much out there on email that one could spend a good chunk of his inheritance exploring the technology.
In the beginning, there was the word and the word was email.
Email's mode of transmission is based on 7-bit ASCII. In other words, early Internet communication was only 128 characters — specifically numbers and letters — that we use in English. Hence no Icelandic, Chinese, Hebrew or Greek, to name a few languages. Also, there were no pictures, or sound clips. The only messages sent were English text.
The mid-1990's was a time of evolution. The ordinary person discovered the Internet and the Internet discovered a new purpose. The first RFCs (Requests For Comments) were coming out, describing a standard for email transmissions of images, sounds, and binaries that would overcome the 7-bit ASCII limitations that had been adopted all those years before. MIME or Multipurpose Internet Mail Extensions, was a new standard meant to succeed the patchwork of binary-to-ASCII solutions.
There are two major divisions of email clients, graphical and console.
Graphical clients are best used when the content, be it text or multi-media, is processed by a person, and human factor plays an important function in both as the sender and receiver of the communication.
Console clients do the same thing as their graphical counterparts, but there is less multimedia support. A console client's great strength is its economical usage of machine resources; it lends itself well to scripting.
Typically there are four links in the email chain:
Composition with a mail user agent (MUA), such as Mozilla. Creating an email is a painless procedure with most programs. It's simply a matter of filling in the blanks.
• The address to which to send the message.
• The subject matter.
• The message, which can include all manner of information including text, sound, and graphics.
• The return address, your email address.
Delivering the message using a message transfer agent (MTA);
sendmailis a good example. Configuring the MTA is normally a one-time issue that happens when using the email client for the first time.
Storing a message destined for a recipient -- the POP (Post Office Protocol) server accesses the message delivered by the MTA. Small ISPs and office intranets often have the same server running both the POP and SMTP (Simple Mail Transfer Protocol) servers. Larger organizations separate the duties, normally for a combination of performance and security reasons.
Message retrieval, once again using the ubiquitous mail user agent.
There are two competing protocols used:
POP3 (Post Office Protocol version 3)is the most common. A client logs in and is able to download the message, with the option of removing it from the server.
IMAP (Internet Message Access Protocol) is best used in an organization where control of the email itself becomes a corporate issue. The email can be accessed from anywhere, but it stays on one machine. IMAP has additional features over POP in that it is capable of doing keyword searching.
Back in those early days, the easiest way for people to learn to email was to associate specific actions with real-world equivalents. Take, for example, the addressing of an email:
- The subject
- Main recipients
- Courtesy recipients
- Privately informed recipients
Hence the terms subject, to, cc (carbon copy), and bcc (blind or blank carbon copy). For those people who were born after the invention of electricity, carbon copy refers to a special composite of paper and ink that when pressed hard by a writing implement, such as a pen, it would produce a number of copies of the same information on several layers of paper. That's how Bill Gates signed his first contract with IBM.
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