Open Rate: The Most Important Email Marketing Metric Ever

  • January 4, 2017

By Verity Jennings

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When evaluating the success of an email marketing strategy, there is a lot to consider.

Image credit: DC Comics


We’ve got our conversion rate to demonstrate how persuasive our strategy is, ARPES (average revenue per email sent) to show us how efficiently our campaign is generating revenue, and click rate to provide some insight into the effectiveness of our body copy, layout, and calls-to-action.

But will any of those things matter if no one opens our emails in the first place?


If we don’t get that all-important “open”, to get the email interaction started off, our recipients will never see our finely crafted emails in all their glory and all of our email marketing efforts would have been for naught.

This, of course, means that if we as email marketers were only to use but a single metric to measure the success of a campaign, that metric would most certainly be our open rate.

Open rate: The most important email marketing metric ever

What it is

An open occurs when a recipient of a marketing email clicks on the email to open it and find out what amazing delights are contained within. What happens from that point on in terms of moving down the sales funnel is a matter for email marketing’s lesser metrics to contend with.

Calculating a campaign’s open rate is exceedingly simple; just divide the total number of emails opened by recipients (aka opens) by the total number of emails delivered to recipients (emails sent minus bounces). Then multiply by 100 to calculate the percentage of emails that were opened, and voila! We have our open rate.

What it tells us

Open rates can give us a clearer picture about several key aspects of our email marketing approach:

  • The health of the relationship between our brand and the fine folks on its mailing list. Are our recipients interested in what we have to say/offer?
  • Customer perception of the brand and the quality of its emails. Are our emails viewed as useless spam from a nuisance, or as something potentially helpful and/or interesting from a trusted source?
  • The quality of our mailing list to begin with. Are we sending our emails to the right people? Have we taken care to actually obtain informed consent before beginning the email marketing dialogue?

But, towering above all these seemingly important email open rate insights is the most important insight of all: The quality of our email subject lines.

Image credit: New Line Cinema


The question of whether email subject lines and open rates are intrinsically linked is one that has been asked and answered a thousand times over already.

With industry-wide open rates that hover well below the 30% mark, the fact is that the email subject line is the only part of our emails that most of our recipients will ever see. It is the single most important part of any email and its effectiveness can make or break an email campaign.

A good email subject line will generate a high open rate, and a bad email subject line will generate a low open rate.

If our emails are not getting opened frequently enough, they won’t be generating enough clicks, conversions, and revenue. It’s almost a certainty that our email subject lines are the problem.

It really is that simple.

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