The only important point to be made here about the hardware connections is that the email system consists of lots of personal computers hooked to a large and complex network of email host computers. Software exchanges the messages behind the scenes, with all of the work being shared among the computers. We'll look at how this happens in a subsequent lecture. Right now, we're interesting in the results of this networking and how to use it. Email is delivered quickly.
Some messages get half way around the world in a minute or two.
Not all messages go that quickly. Some may take as much as a day to reach their destination. In any case, it is much faster than snail mail. The advantage comes in the speed of the reply. You are likely to get an answer to an emailed question while you still remember why you asked the question.