Alan's HINTS & TIPS - Sending e-mail - how does it get there?

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SENDING EMAIL - How does it get there?

This is the NOT SO SHORT version - or you can view the SHORT version.
What actually happens when you send your e-mail from the computer? Well, in a not too technical way I'll tell you.

All the data or information in your computer is moved about in digital form. That is, it consists of entirely ON and OFF pulses that make no sense to the average person. However, to get information from the computer to another computer which might be hundreds of miles (kilometres) away it generally goes via the telephone lines.

Morse Key

Telephone lines were initially designed to take morse telegraphy (morse code) and this was just a matter of sending a voltage up the telephone line each time the key was pressed. This in turn was received at the other end by an operator who listened to the clicks made on a sounder, basically a relay without contacts - it just rattled up and down in sympathy with the voltage it received.

Telegraph Sounder

Of course later on developments enabled speech to be carried over the telegraph lines and hence the arrival of the telephone. This brings a problem for the computer world, they wanted to send on-off pulses again and a way had to be found to achive this without messing with the existing system. The answer was the Modem.

A MoDem is a Modulator and a Demodulator all in the same package. This actually means that the ON-OFF pulses are converted into a series of tones instead of just ON and OFF voltages. When the voltage is high one tone is produced and when it is low a different audio tone is produced. This is called modulation.

When you want to send an e-mail (or connect to the Internet) your dial-up requester comes on the screen and you request it to "Connect". When this happens it tells the computer to dial up the telephone number for your ISP - Internet Service Provider.

On some computers you can hear the modem sounds as it dials the ISP's number and the first handshaking tones, after which the sound is muted to avoid you being driven mad by them.

When the ISP answers the phone it detects the signals being sent by your computer by using a Demodulator which converts the tones back to ON-OFF pulses again. The computers do a bit of "hand-shaking" - checking each other out - your user name and password is then checked to verify you are one of their customers. Once this is complete the ISP processes the information you are sending - in this case an e-mail.

Your ISP collects your e-mail then checks to see if there are any new e-mail messages for you. If there are they are sent to you by the same process and in most cases your computer is set to disconnect from the ISP when you have cleared you mail.

The ISP then sets about the process of delivering your message/s to the appropriate location - the ISP of your friend or other recipient.

The wonderful world of the Internet keeps track of all the other ISP and each country has their own specific Internet identity. Once your ISP checks your e-mail it goes off to the correct country and from there to the ISP whose address is on the e-mail.

When your friend or other recipient checks at their ISP for their e-mail your message is delivered to them in the same manner as it was sent from you to your own ISP. Generally this all happens in less time than it takes for you to get to your door when someone rings the door bell. Pretty smart eh?