What Exactly is Email Open Rate and How is it Measured?

February 20, 2022

Whenever we send out an email message we always want to know what the open rate was and how we can improve it.  The answer to these two questions might be harder to find than you realize.

Let’s take a look at how email open rates are measured and what can cause the figures to be recorded incorrectly.

When you send out an email to an address list using an email marketing service or software program, you are able to track a number of metrics relating to that email.  For example:

In this example 672 emails were sent out.  668 of them were delivered.  Of the 668 that were delivered, 112 people opened the email at least one time.  You can also see the number of emails that bounced (didn’t reach their destination for some reason – another topic all together), how many people unsubscribed and how many unique clicks there were.  For now we will concentrate on the open rate.

In order to fully understand the importance, or lack thereof, of the open rate figures you need to know how that figure is measured.

When you send an email via your email marketing service or software, an invisible piece of tracking code is sent with it.  This code is sent as an image but is invisible to the recipient.  When their browser or email software (i.e. Outlook etc.) displays the email on their screen it also reads the code and responds to it.  All of this happens automatically.

Each email is given a unique tracking code so your email marketing service or software can tell not only if the email was opened but also who opened it.

“What an excellent idea,” I hear you say.  It would be if it were just that simple.  Here’s the problem – or should I say problems.

Just the fact that the browser displayed the email doesn’t tell you anything about whether or not the recipient actually read it.

Also, the email marketing service can respond to the tracking code even if the email wasn’t actually opened.  If the recipient uses software (such as Outlook) and the email is displayed in the preview section, the tracking code is still activated.  Therefore the reader could delete the email without even looking at it. As long as it displayed in the preview pane, you will think they opened it.

And there’s more… because the tracking code is attached as an image: if the recipient has images blocked, only reads text emails as opposed to HTML, or reads it on a mobile device, the image will not be displayed and the tracking code will not be activated.  This means that sometimes someone will see the email but you don’t know that.

What does all of this mean?  It means that you shouldn’t be so concerned about the open rate of an email.  Although it is an important part of the puzzle you should look at the big picture.  Also track which links were clicked on and what people did once they arrived on your landing page.