Email is the electronic equivalent of the letters which you receive and send each day through the mail, hence the name, Electronic Mail.
Email is probably the most used aspect of the internet at the moment.
And you usually get one emailbox with one internet dial-up account. Let's look at a company with 200 employees. Many individuals, over the course of their lifetime will move, necessitating a change from one local Internet dial-up provider to another. As well, you probably subscribe to a number of automated services, ALL of which will not know of your new e-mail address. These problems often make people wary of changing their dial-up provider, even when they want to, because of the effort and disruption involved.