Components of Email

Components of Email

What are the components of email?

The headers are pieces of information that tell you and the Email system a number of things about a particular piece of Email. Each of these headers has a specific name and a specific purpose. You will see some, but not necessarily all of the headers each time you read a piece of Email. You have to fill in all of them; they are all generated and put in the proper form by the Email program you use.

Here, I have covered the most important header lines. However, you should understand there is considerable variation in how the lines may be constructed.


Header Type Description
From This line shows who sent the message.
Return Path This tells your mail program where to send a reply if you choose to respond to the message.
Date This shows the date and time that the message was sent, according to the sender’s computer.


This shows the user ID (Email) of the person to whom the message was addressed. This means that if the message is for you, this line will contain your address. If the message was also sent to other people, their addresses will appear on this line as well.


This line shows any user IDs who are to receive copies of the message. That is additional recipient(s) of the message. (Ce is an abbreviation for “carbon copy”, a term that is outdated but still in use.)


This line shows the subject of the message. This is a short description that is typed by the person who composes the message. If the subject starts with the letters Re:, it indicates the message is a response to a previous message. For example, say that you send a friend a message with the following subject:
  Subject: Congratulations! Party next Saturday?
  If your friend uses his mail program to send a reply to you, the mail program will automatically insert the characters Re: at the beginning of the subject: line. Now the subject line will look like this:
  Subject: Re: Congratulations! Party next Saturday?
Reply-To or Return-Path Think of Re: as meaning “This is a reply to the previous message with the subject… Your Email application automatically uses this address when you reply to the message.
Received Contains information from each host service that relayed the message
Message-ID The unique ID that identifies this message (generally not useful)
X-Sender Adds a layer of authentication to the message by identifying the sender
Mime-Version The version of MIME used (the Multipurpose Internet Mail Extension is used for attachments and for HTML-formatted messages).


Content-Type The MIME data format used Frequently, the data format is text/plain with some further information to identify the text type.
Lines Number of lines of text in the message
X-UIDL A unique identifier added by some POP Email applications to identify messages that have been downloaded


Message Body

The second you are you part of the message is the actual content of the Email; what you send and what you receive. When sending Email to a computer system where your message will be interpreted by a computer program, will be given instructions to use specific words or phrases in the message body.


The signature is not a signed name but a sequence of lines usually giving some information about the person who sent the Email. It’s optional and it is made up of anything the user wants to include. Usually a signature has the full name of the sender and some information about how to contact the person by Email, phone, or fax.

Many people also include a postal address, description of their organization, job title, and even favourite quotation or some graphics created by characters typed from the keyboard.

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