Read Rate (deliverability)


Read rates are a metric that you typically see in deliverability monitoring programs such as Inbox Tracker by Sparkpost (formerly eDatasource) and Validity (formerly Return Path). This metric is similar to the open rate but with a crucial difference in how they are measured.  A Read event is measured (or counted) when a subscriber marks the email as read in their email client; the same way an ISP counts “opens” or reads. While an Open is measured when a tracking pixel (an image) is fired by the receiver downloading images in the email. These services use a panel of people that agree to have their inboxes monitored to collect this data to create a estimated rate the email was read. Because an email is counted when it is marked as read these are unique rates not total rates.

The open rate shows the percentage of people that downloaded the pixel image out of delivered email (see Open or Render Rates).  Open rates tell you how many people in your list opened (and presumably read) the email, while Read Rates tell you how many people in the panel read the email. Some of these systems also provide the related Read + Delete metric, which is the percentage of who marked the email as read and then immediately deleted it.  Since the Read Rate is a click based metric (you select the email), not a pixel based tracking method it may not be affected by Apple’s Mail Privacy Program.

Tips for interpreting data.

Overall higher is better, as it indicates a larger percentage of subscribers are engaging with the email. Since read rates use the same methodology as ISPs, like Gmail and Outlook, for some senders this may more accurately estimate what ISPs are calculating for your “open rate.” When interpreting data it is important to understand the difference in how they are calculated from open rates as well as the fact they are estimates. When comparing open rates to read rates, be sure you are using the unique version of the open rate, not total open rate or the read rates will be substantially lower.  Unique opens and reads are both only counted once for a given address and email combination, hence they tend to produce similar rates. Since read rates are estimates of your list performance based on panel data, some difference is expected when comparing to unique open rates.  Combined with open rates, read rates provide a more comprehensive understanding of subscriber activity and ISP’s views of it.

Related Links

Validity (Return Path), “Read Rates: The Secret Ingredient to a Successful Email Marketing Program” 2016:   

Sparkpost (eDatasource) “Whither Read Rates and Why?” 2018: