When measuring the success of email marketing campaigns, the metrics most often tracked are open and click-thru rates. While those are noteworthy statistics, unique clicks to unique opens which I call the Engagement Rate is a very important, yet often over-looked measure of the overall success of a campaign. 

Most companies calculate click-thru rates as the number of clicks/number of emails delivered (clicks either being total or unique).  What the click-through rate doesn’t provide insight to is the percentage of overall readers who find your email useful or relevant. 

The click-thru rate doesn’t distinguish between a scenario in which you have 10 subscribers (an anemic number for a list but it makes the math a lot easier) and 1 user clicks on 10 links in an email and 9 subscribers open the email but do nothing and a situation in which all 10 subscribers each click on a single link.  In both cases, the number of clicks is 10 and the number of opens is 10; however, I would argue that in the later scenario, you have a higher level of engagement with your readership because each of your subscribers each found something in your email of relevance.

That doesn’t mean that traditional click-thru rates aren’t important, but the tracking the engagement rate will help you make sure that you are providing value to as many of your subscribers as possible.  If your engagement rate is low or declining, it may be that you campaigns are too general and you should offer multiple, more targeted emails or try segmenting your audience and include more specific content. 

In any case, the engagement rate provides another way to look at how your e-mail campaigns are performing and that additional insight will help you make them even more effective.