Can I trust my Marketo email open rates?

Have you ever looked at an email report in Marketo and wondered why you have more clicks than opens? How can someone click a link in one of your emails without actually opening the email?

The answer lies in the way which Marketo measures opens in Gmail.  If you use Gmail, you are probably familiar with the “Display Images” option which sometimes appears in your emails.


By defualt Gmail does not display images. Marketo measures whether or not you opened an email by whether or not you choose to display images in an email. Since Gmail is one of the most commonly used email clients (in 2012, Gmail had more than 400 million users while Outlook only had 25 million) it’s likely a high percentage of your Marketo emails are sent to Gmail accounts, even if they don’t have gmail addresses.

According to a study by Silverpop, the average Click to Open Ratio (CTOR) is about 19%. But because people might not be displaying images, this average (as well as your own data) may be inflated.

If your emails are structured in a way that does not require a reader to display images to understand them, your email recipients probably don’t display images. If a lead opens such an email and does not choose to display images but still clicks one of the links in your email, Marketo will register the Click but not the Open. Thus Marketo might be reporting your CTOR much higher than it actually is. This inflated ratio is not an accurate measure of the effectiveness of your emails. To truly measure CTOR, you need accurate recording of all opens.  There is no certain way to measure CTOR: if your leads don’t display images, you cannot track their opens.

There is something you can do to try to improve the veracity of your open rate data: give your readers an incentive to display images.  For example, you might center the introduction of the email around an image or video.  By talking about the image or video in the email, the reader may be more enticed to display images. Furthermore, it helps to enter text near the image to prompt the reader to display images (“Click display images to see the ridiculous photo which I am talking about”).

One expert at this is Ramit Sethi of  His emails provide fantastic incentives for his consumer audience to display images.

If the data will never be perfect, why bother improving your open rates?

One reason is deliverability: when leads click to show images, they demonstrate a trust in your emails, a trust that can be extended to 400 million other Gmail accounts.

Even if you can’t trust your open rates to be 100 percent accurate, you should continue to test subject lines to increase your open rates over time.