Joran Hofman
April 4, 2021

What is a Header?

In computer science terms, a Header is the complementary data that is placed at the beginning of a group of data created for the purpose of being sent or stored.

Some examples of cases in which the use of "headers" is appreciated are:

  • In the header of an email.
  • When a data packet is sent via the Internet Protocol (IP).
  • In cases where a data packet is sent via wireless communication and magnetic media.
  • Graphics file formats have headers with information such as resolution, size, colors, among others.
  • Headers are used in archive file formats to specify the file format and software.
  • We can also get headers in various programming languages to express functions.

What is an Email Header?

An Email Header is a part of an email that is placed before the body of the email and contains information about the person sending the email, who it is addressed to or from, the subject of the email, what is the process of transmitting the data, other technical details describing the content of the data (metadata), etc.

What is an Email Header for?

Email headers serve multiple purposes.  Among the 3 main purposes are:

  1. Shows the routing of the email: 

An email header serves to identify which is the route of the emails that are transmitted through the Message transfer agents. 

  1. It helps to reduce spam: 

Emails display information in the header that helps providers who provide transmission services to prevent spam problems.

  1. Provides information about the recipient, sender, and date: 

In every email, you can see who is sending it and where it is going. This information is located in the mandatory fields "To," "From," "Date." There is another type of optional information that can vary from one provider to another.

What data does an Email Header contain?

There are many types of Email Service Providers (ESPs), and depending on the one used, the email header may contain different data.  Some of them can be:

  • From: information about where the email is coming from.
  • To: who the email is addressed to.
  • Subject: what the email is about.
  • Date: is the exact time (date and time) that an email was created.
  • Return or Reply To: is the address to which a reply will be sent.
  • Envelope-To: shows that the email was sent to the subscriber's mailbox.
  • Delivery Date: is the time (date and time) when an email customer receives the email.
  • Received: shows the path of the email through the servers until it reaches the recipient.
  • DKIM (Domain Key Identified Mail) signature and domain key signature: this helps identify the email signature.
  • Message ID: is a unique sequence of letters and numbers that identifies the email message when it is created.
  • MIME (Multipurpose Internet Mail Extensions) version: in the email header, you can also see which MIME version was used.
  • Content type: indicates the type of email content, which can be plain text or HTML.
  • Message body: this is the message that is transmitted in the email.
  • X-Spam Status and X-Spam Level: the first is a score given to the email to determine whether the email is Spam or not. As for the X-Spam level, it is shown in a ratio of 1 asterisk for each point received.

Best Practices for Creating Engaging Email Headers.

An email header has multiple and varied creative ways to be personalized; who would have thought? Yes, just as you hear it, this is a golden opportunity that you can not miss to engage customers or readers.

Some practices that I recommend to achieve this are: 

Company name and logo.

A company's logo includes its name in most cases.

If the company is new, this will make consumers get used to your brand and the products or services you offer. So be sure to put your company's name on every email you send out.

However, if your company is widely known, you can omit the name and place only the logo. For example, this type of strategy is often used by the American corporation NIKE that we all know.


The header also allows you to place a menu, fixed or interactive, which serves to guide readers navigating to your website. 


Finally, to make a design that captures the attention of the people to whom you address the emails.

I want to share what for me are the "Best Practices for Email Header Design":

  1. Add a link with the option "View in browser (web version) to increase the possibility that people will click on it.
  2. Customers today always want to save time when searching. If you incorporate next to the logo and menu a link to a store locator that shows which stores are closest to them, you will make their task easier, and faster and they will thank you enormously. This search engine can even have a web map service like Google Maps to give visitors a more satisfactory experience.
  3. Just as saving time is a priority for consumers, so is saving money; that is why the email header can display information about discounts or price reductions on products or services to capture their attention.
  4. Another way to take advantage of the email header’s use is to inform the reader about the products or services you can offer them.
  5. Incorporating in the email header a link with the option "My account" can make people click on it after reading the message’s content and browse your website.
  6. In these tips I give you, I can not fail to mention one of the most used forms of communication in the world, as are the "social networks." The icons of your social network accounts can be placed in the email header to attract the reader's attention, who usually sees them at the bottom of the messages. 
  7. Another tip is to change the color and texture of the email header’s background; this will keep the customer from getting bored.
  8. This field can also be modified to adapt it to the different seasons or change of seasons, for example; you can make spatial designs for the summer season, Valentine's Day, Thanksgiving, Christmas, etc.
  9. You can animate your company logo or make use of GIFs to give strength to your brand. The size should not be larger than 1MB to ensure it loads correctly.
  10. The header menu can be more eye-catching if you use custom fonts.
  11. You can also add an "Update preferences" link for readers to update them at will.
  12. A tip is to put the date in the header of the email so that the reader knows at a glance when it was received.
  13. Another way of design can be not to place a header so that the reader does not notice when the header ends and the banner begins.
  14. If you prefer, you can place a personalized photo of the sender. This tip gives a touch of formality to the message that you want to transmit. An example could be an informative news channel that places the photo of the journalist who writes the article or a gluten-free and organic food cooking blog that places the photo of an expert on the subject.
  15. The email header is an inexhaustible way to promote your company; a smart way is to place a call to action (CTA) message that, when clicked on, directs the reader to your website. An example can be "Do it now," "Subscribe," "Register now." 

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