Working With Email, Part 1

Getting to Understand The Plumbing System


In the last post, We made a date to start exploring at this ancient channel of communication in terms of how it works.To do that, I think it makes sense to start from an angle of what we know about computers, and how they communicate and then narrow it down to what we are interested in.

During the introductory post, we saw that an email client requires a method to receive and send messages, in addition to displaying them for viewing. That last bit is not a problem, so we will leave it for the future posts.

Of Ports and Addresses

Every computer on earth is unique in its own right. I mean unique, not in terms of its brand or operating system. Certainly, this is not what sets your machine apart from others.

By machine, this refers to anything with a processing unit, be it a mobile phone or a desktop computer. All these devices can be classified as computing machines.

Now, this uniqueness is what defines a machine's identity in the same way your identity is defined by not only your name, but even more important by your personality.

This has the advantage of identifying one machine from the other in a clear manner.

If you want to communicate with someone, they have to know your personal details. These could be

Your name

Either in full or nickname. Anything that sets you apart from whoever are around you.


I think this one is the most important thing of all:

  • It could be a traditional physical address;

  • a postal office address;

  • Or your electronic address such as your email, Twitter ID or Facebook UserID.

Your phone number

It could be a fixed or mobile phone.

But why bother about this concept of addressing?

Because that is exactly what is behind computers: every computer has its own address to which other machines address their messages.

Let us put it this way: the idea of machines communicating is modelled along the same lines as human communication. In particular, transport.

A port is a point of departure and arrival. From this outlook, it means computers use ports to send and receive messages.

Even within a computer itself: the way it transports information from one component to the other, for instance a keyboard to the processor, is made possible because of these ports.

However, we are simply interested in how two different machines find each other on the network: this is made possible by the controlling hub or server. This server registers all machine IDs.

For the sake of this discussion, this is a mail server. However, it reflects any other communication that takes place through other protocols.

Your machine has dedicated ports to receive and send messages. These are in brief,

25Outgoing Unencrypted for POP
110Incoming Unencryptted for POP
995Incoming (secure) for POP
993Incoming (secure) for IMAP
465Secure outgoing for IMAP

From the above table, you will notice that we have ports for incoming and outgoing messages, for either PO or IMAP. Below we will get into that in detail.

For the meantime, let's talk about how our email addresses are formed.

Of Email Addresses and Identity

Before going further with this discussion, let us take a detour and talk of our email addresses, in light of how mail servers work.

While machines have got addresses for identifying each other, these are often expressed as a series of numbers. This address could be an IPV4 or IPV6, but the bottom line is that it is difficult for humans to remember such.

Then enters the translation service that is done by the Domain Name Service. So on the Internet, we have servers and clients:


Those machines that have got the resources we have to share. Or put simply, a machine with the data that the other machines want.


Those machines that request that data for consumption.

So every machine can fall into either the client or server category, depending with its functionality.

Now, there are those machines that hold messages which we send and receive. Most of these are housed by big corporations, universities or research institutes. This means that as an ordinary person without lots of funds, all what you have to do is get yourself an address with these companies' mail servers.

A mail server hosted by Microsoft could be known as the Outlook server.

The same applies with Gmail which is hosted by Google, that popular search engine.

  1. You apply for an email address.1

  2. You are required to choose a username. This username is your identity on that server alone, which means

    • It must be unique for the mail server.

    • It does not need to be unique for all other servers in the world.

    • The uniqueness of your username throughout the world will be as a result of your final name on that mail server.

  3. You are provided with an ID for the server.

  4. Then you will have an address that says, "you on this mail server", otherwise indicated by an @

Thus, an address such as means,

  • This user is John

  • Found on the mail server.

Of Message Retention and Syncing

Next in understanding this communication chain is the delivery of messages themselves.

When you get your messages, do you want the server to retain a copy of your message or not? This can better be understood again in terms of traditional mail delivery:

  • When the postman or postwoman delivers your letter, they do not keep a copy of that letter.

  • On the other hand, this is the internet age: you are not bound to one place. Anywhere you are, you should be able to get your messages and read them from the server.

These two approaches are reflected in the two main methods of how email is delivered to its recipient: the POP and the IMAP protocols. POP is short for Post Office Protocol, while IMAP is short for Internet Message Access Protocol.

  • With POP, when you get your messages, they are deleted from the mail server, while

  • With IMAP, you can always have a copy on the mail server.

The advantage of IMAP over POP is that you can always access your messages, even those you already read, anywhere. However, with POP, once you pull your messages from the server with your email client, they are deleted from the server.

This means that when your machine crashes, without a backup to resort to, you can lose your messages for good.

Because of that, people are often advised to use IMAP, unless there are other compelling reasons not to do so. For instance, most corporate mail servers can only hold that much amount of mail, and delete the rest. In that case, you will have no choice.

Anyway, we will discuss this in a future post on email clients.


Email works because how computers communicate. the mail server routes messages on the network to the desired destinations based on machine addresses.

The idea of how this communication takes place is the same as the traditional method.

In the next post, we will look at email clients: what they are, and what could be the difference between accessing messages on the web and on the desktop.

Let's meet then. Thank you for reading this post.



By "application", this could be a free or a paid service.

Ishe Chinyoka
Ishe Chinyoka
Access Technology Instructor

My research interests include operating systems, access technology, programming, and science fiction.