Design & Development

Email: How It Works

Email has become one of the primary sources of communication among people in the world today, yet how it works remains a bit of a mystery to many people. In order to shed some light on the subject, let’s follow an email message from the sender to the recipient.

Most people use some sort of email client in order to send, receive and organize their email, which is an application such as Outlook, Entourage or Mail. The first step in sending an email is to compose the actual email, which usually opens up a blank email document in the email application. There are two sections to this document, which are known as the header section and the content section.

What’s in a header?

The header section contains information about the email itself, such as the address it is going to, the address it came from, the subject of the email, the application used to create the email and much more. Most of us will only ever deal with providing the recipient address, CCs or BCCs, and the subject of the email, since most email applications automatically fill in the other header information.

Once we have established where the email is going and the subject, we move on to the content section, which holds the message and any formatting information needed to convey the message. Once we have completed our message, we are almost ready to send the email. The final step is to add any attachments, which are files that are going to be included with the email when it is sent. Now we are ready to send the email, so we click the “send” button in our email client. So what happens next?

Communicate with outgoing mail server

The first thing that happens is that the email client contacts the outgoing mail server defined for the email account you are using. In most cases, the server will require a username and password to authenticate the user, and then it will allow the message to be copied to the mail server. From here, the headers provide the necessary information for the mail server to send the email to the destination server. When the message arrives at the destination server, it is passed off to an incoming mail server, which will determine which user the message is intended for (the part before the “@” in an email address), and stores the message for the recipient.

The final step in the adventure that our email has endured comes when the recipient of the email fires up their email client. The email client will then access the incoming mail server for the recipient with the correct username and password, and the messages on the server will be copied to the recipient’s computer and displayed by their email client. An interesting note here is that once the email is copied to the recipient’s email client, it is not always deleted from the mail server, which can cause the mail server to fill up with messages and refuse new mail. Most email clients provide an option to set how long messages remain on the server after being retrieved.

Brian Getting
Brian Getting
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