Email Opens: What Are We Actually Measuring?

When we send out an email campaign and collect engagement information, we take for granted that a click is a click and an open is an open. In the former case, this assumption is fairly safe. We have reliable ways of telling when somebody clicks through to another page. In the latter case, however, things aren’t so clear-cut.

What we think we’re getting

Most people consider an email open anytime a user literally opens an email. In other words, an open occurs when a user clicks on a message in their inbox and views it, either in the preview pane or a separate window.

What we’re actually getting

The main problem with tracking opens is that email marketing software can’t see into your users’ inboxes. Instead, they rely on tracking communications coming in and out of the recipient’s inbox. Clicks aren’t a problem because the act of clicking a link takes a user to an external page, which can be measured. Opens, on the other hand, occur entirely within the inbox.

To address this problem, email marketing software providers have created a sneaky workaround. They automatically include a tiny, transparent image – as small as 1 by 1 pixel – in your email HTML. When the user loads the images in the email, the pixel is downloaded, notifying the system that the email has been has been opened.

The “opens” counted in your email dashboard actually tracks the number of times this tracking pixel has been loaded.

The problems with the tracking pixel

The tracking pixel, also called a web beacon, is far from a perfect measure. Depending the recipient’s email client, the recipient’s email settings, and the sender’s email marketing software, opens can be overcounted or undercounted.

Opens are undercounted if

  • Images are disabled by default – Many email clients, including Outlook and Gmail, have images disabled by default. (You can tell because they’ll prompt you to “Display Images Below” or “Re-enable the blocked features.”) This becomes a problem for email marketers because the tracking pixel only loads if images are enabled. Users can open the message, read the textual content, and not show up as an open, if they never enable images.
  • Recipients opt for text-only emails – Some users choose to receive emails that contain only plain text. Because it’s an image, the tracking pixel can only be included in HTML emails. Opens from text-only recipients are another blind spot.

Opens are overcounted if

  • Images are enabled by default – Some users will opt to enable all images from a particular sender or enable all images in general. In this case, the email marketing software will register an open each time the user clicks the email, even if it only shows up in the preview pane. Likewise, a quick open and close to remove the “unread” status would also be counted as an open. Some email clients will also register opens while selecting the “Mark as Read” option.
  • The recipient has an autoresponder set up – Automatic replies – out-of-office emails and the like – will be counted as opens by some less advanced email marketing software.

What it all means

The number of email opens or open rate in your email dashboard is never going to be 100% accurate. The 500 opens that it shows aren’t really 500 people who opened the email, but a mix of people who opened with images enabled, opened then enabled images, or just accidentally passed through. There’s also a whole other group of people who legitimately opened your message without ever being counted.

At this point, you might be thinking, “Email opens are totally unreliable. What’s the point of tracking them? Should I even pay attention to these metrics?”

The answer is, while email opens will probably never be a good indicator of the exact success of a message, they can be useful as a measure of relative success. By sending two different messages to similarly comprised lists of contacts, you can use your email marketing software’s opens metric to get an idea which message is more successful in securing real opens.

Some areas of an email – mainly the subject line, from name, and preview text – has to be evaluated using opens and open rate. That makes the totals calculated by email marketing software vital for optimization these areas.

That said, you’re still going to want to prioritize more concrete measures, like click-throughs and form completions, where possible. These metrics will be much more dependable indicators of campaign success.

Let us know what you think:

  • Did you know how email opens are measured?
  • How much of an impact do you think open inaccuracies have?
  • Do you have any special rules for working with opens and open rate?

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