Most people are familiar with the operation of ordinary mail.
I write a letter, address it and deposit it with the postal service for delivery. Along with many other items it is sorted and transported towards its destination until it is deposited in a mail box corresponding to the address on the package. Ultimately it is collected from the mail box and read. Electronic mail works in a similar fashion. I write a letter on my computer, address it appropriately and send it to another computer to which my computer connects.