Domains, names and how it's organised

Although the more personable and immediate impact of the Internetís star PR turn -- the World Wide Web with itís multimedia and hypermedia documents -- has been in the limelight, electronic mail is easily the most important use of the Internet. For while other forms of messaging (notably X.400 and MHS are hovering about nervously in the background) Internet mail has really caught the imagination of many, and with a reported 28% of transatlantic data being carried on the Internet, commercial users are already thoroughly involved on a day-to-day basis.

Like a fax, email can be dealt with at the convenience of the recipient. Unlike fax, it is routed directly to the userís mailbox and straight to their desktop if they happen to be logged in; so it can alert them the moment it reaches them.

But fax is mainly losing ground to email for the best business reason in the world: itís cheaper. Lots cheaper. A £5 fax to the USA costs maybe 20p to send by email, although the absolute costs depend on what type of connection to the Internet you employ.

Whatís more, it arrives in seconds, not minutes, and it arrives in the same medium a it was sent. A received fax is generally a third generation output by the time the reader gets it, and anything can happen along the way, including marks on the fax scanner, scratches on the output drum, dark rings on the thermal paper where the secretary has stood the coffee mug. You know the sort of thing.

Anything you can do...

Fax is limited to a resolution of 200 lines per inch. Most users opt for the lower resolution to save connect time costs: even when the fax is sent directly from a computer and not via an intermediate scanning process.

Attachments to email can be at any resolution you like, since they can be data for your local programs, that can produce full colour reproduction at 3000 lines per inch, if you need it.

In other words, email is data communication made simple, where the sender and receiver need know nothing about bauds and bits, nor DTE rates and ISDN versus leased connection.

An aspect that users appreciate immediately is the ability to comment directly on the incoming messages and turn them round within seconds, so sending other documents as attachments should be restricted to "necessaries" only, as this impedes one of the prime benefits of the basic email service.

Creating all your messages in, say, Wordperfect, and attaching the Wordperfect file to a massage saying "please find herewith a WP file" does not endear you to the recipient who just wants to see it and reply!

email can be a very stark communication medium, devoid of all formatting. Various devices such as the ubiquitous smiley :-) have been devised to replace some of the emotion, and try and avoid "stark" being interpretted as "rude".

Assured delivery

Using the resilient and ubiquitous IP addressing scheme, mail is routed through the Internet for delivery in a variety of different ways.

A user of email has an address, which, in the case of a company based in the UK is as simple as:

yourame@yourcompany.co.uk
Blindingly obvious? Try telling that to users of mail services such as CompuServe which are simply random numbers.

If you subscribe to one of the many new Internet email handling services, you will be given an address that reflects their "domain", which is IP-speak for the part of the address that identifies the keeper of the mail post office system. It looks like:

yourname@handlingco.co.uk.

Here handlingco is the domain name. But yourname can still represent your name. If you happen to be called John Smith, then there is a problem, but this is usually dealt with by variations on the theme such as jsmith, jsmith1 -- not original, but better than 34545,7683576 and random number generation.

And whatever your name ends up as being after avoidance of duplication, this is aliased to your chosen name anyway. jsmith will be placed in the header of the message as John Smith by the software that creates the message, even if the unique Internet identity is dq679365.

In addition to the Domain Name, there can be an individual host name that appears immediately to the right of the @:

yourname@hostname.domain
The host name is usually the name given to the local system, it is optional for the mail user, although network administrators rejoice in devising suitable "family" names. Planets, stars, girlsí names, islands: you name a "grouping" and some network admin. somewhere is likely to have named his clutch of hardware after it.

User names and host names can be allocated locally by the mail service operator. Domain names are more important since these are the public addresses that help route the mail to the post office, and these are administered centrally.

Also involved is the allocation of the IP addresses themselves, those 32-bit network identifiers that are part of the central structure of the Internet, since TCP/IP knows nothing about jsmith@anywhere until anywhere has been mapped to an IP address format that it can understand. Hence the Domain Name Servers that exist on the Internet that map names to addresses at the request of client applications.

Paul Lavin ponders that cheap email solutions can be misleading

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