To be successful with an email marketing campaign, it’s important to accurately measure and analyze your results over time. So which email marketing metrics are most important?

In this guide, you’ll learn all of the significant email marketing metrics every marketer needs to know, and what each of them means.

The Importance of Email Marketing Metrics

By some measures, a well-executed email marketing campaign can yield you a return on your investment of 38:1, thanks in part to the low costs of designing and executing a strategy in the first place.

But another part of email marketing’s staying power is its sheer potential for revenue generation; the right offer, the right timing, and the right recipient can lead to an instant sale.

The Most Valuable Email Marketing Metrics and KPIs

Now let’s get down to business. There are dozens, if not hundreds of email marketing metrics to measure with regard to your email marketing campaign, but these key performance indicators (KPIs) are some of the most objectively important:

1. Open rate.

Your open rate is probably the first metric you’re going to check, and it’s definitely one of the most important. This figure will tell you how many people actually opened your email, compared to the number of people you sent it to.

Depending on which email marketing platform you’re using, this might be represented as a number (e.g., 50 out of 200 people) or a percentage (e.g., 25 percent). Either way, this metric represents the first major gate between your email subscribers and real revenue, and is an indication of the strength of your subject line (though other variables may also be at play).

People are busy, so you’ll need something catchy and relevant to get the open rate you want. Be sure to see our post on sales email subject lines for help here.

2. Click-through rate (CTR).

Click-through rate (CTR) is the number of people who clicked a link, presumably to your site, that was included in the email. Depending on which email marketing platform you use, this could be presented in a few different ways.

Most commonly, it’s displayed as a percentage of total recipients who eventually clicked a link, so it partially depends on your open rate. In some cases, it may be presented as a percentage of people who opened your email first.

After taking factors that influenced your open rate into account, this statistic can tell you how attractive your email offers were, and whether your links were appropriate for your audience.

3. Unique clicks and opens.

Clicks and opens will tell you how many total instances of opening emails or clicking links occurred within your subscriber base, but this can be obscured by individual users opening your emails or clicking your links multiple times.

Though rare, it’s hypothetically possible that a single user could be responsible for all your opens and clicks. Unique clicks and unique opens, however, will tell you how many individual users took each of these actions, allowing you to filter out duplicated efforts from isolated, diehard fans.

See my guide on email tracking for info on how to calculate this metric!

4. Click to open ratio.

This is a good metric to track if you want to examine the relationship between your clicks and email opens.

“If you have low click-to-open ratio, it means lots of people are opening your content, but they don’t get very far when reading it; in other words, you have an email content problem, either in your design, your body content, or how you present links,” says Jeff Richards, Head of Content, Essaytigers.

If the ratio is high, but you’re still not satisfied with your overall CTR, it means not enough people are opening your emails in the first place—which means you’ll need to polish those subject lines or work on your sales targeting.

5. Conversion rate.

If you’re familiar with online marketing at all, you probably understand what a conversion rate is.

The exact nature of a conversion will vary based on your industry and your intended goals; for example, it might be a purchase on your online store or a customer filling out a contact form.

In any case, it’s a valuable action taken by one of your email subscribers.

Here, conversion rate refers to the percentage of email recipients who eventually take some valuable action, and it’s a good picture of the overall value of your campaign thus far (though as we’ll see later, there are even more precise measurements to calculate).

6. Email bounce rate.

Email bounce rate refers to the percentage of emails that were not delivered to their intended recipient.

This can happen for several reasons, which we cover in more depth in our article on email bounce rates. Note that email bounce rate is separate from a normal bounce rate, which measures the number of web users who leave your site after only visiting one page.

In both cases, a high bounce rate is usually not a good thing.

7. Spam percentage (or spam score).

Some email platforms give you tools to measure a qualitative “spam score” for your email drafts, before you send them out.

Internet service providers (ISPs) fight actively against spam by blacklisting emails from specific domains or services when a known offender is flagged as spam too often, or when violating certain spam-related protocols.

Monitoring your spam score proactively will help you avoid features that would increase your likelihood of being marked as spam, being automatically sent to a spam folder, or getting you blacklisted.

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Common triggers include too many links, poorly worded links, and spam-like wording, such as multiple exclamation points.

8. Spam complaints.

Even when keeping an eye on your spam scores, it’s a good idea to monitor the number of spam complaints you receive from your subscriber base. Determine if there’s a pattern, and cut any tactics you think may be responsible for causing more people to flag you as spam.

Take spam complaints seriously, because if you get too many, it could mean the end of your email marketing campaign. For more info, see our post, Why do Emails Go to Spam?

9. Unsubscribe rate.

Though potentially less punitive, unsubscribe rates are still something to watch closely. When someone unsubscribes from your email newsletter, it means they’re no longer interested in your content.

Sometimes, this can’t be helped—people develop new interests and move on. But most of the time, this is directly or indirectly your fault. It could be a drop in content quality, sending emails too frequently, using the wrong email newsletter templates, or emailing irrelevant content to your subscribers.

10. List membership.

Unsubscribes aren’t the only list-related metric to watch, either. Pay attention to how your list memberships are growing, especially if you have multiple list segments. If there’s a spike or a plummeting trend in one of your lists, see if you can figure out what spurred it.

Use data visualization to see if there’s a clear correlation between the types of emails you send and how your subscriptions evolve.

11. Forwards and shares.

Forwards and social media shares are two separate metrics that essentially mean the same thing; someone has found your email’s content valuable enough to share with a wider audience. This expands the reach of your messaging and also proves that your content was valuable enough to warrant this extra action.

Carefully analyze the qualities of your emails that result in forwards or shares, and play them up in your future blasts.

12. Days and times.

In email marketing, timing has a massive impact on your success. Sending an email on the right day at the right time can easily multiply your results, many times over. While there are some general rules to follow (like avoiding email blasts on Friday afternoon), the “perfect” time varies tremendously from company to company.

You’ll have to send emails at varying times of day and days of the week, then monitor your results across those time periods to discover the timing pattern that works best for your subscribers.

13. Opens by device.

It may also be worth paying attention to your open rates per device. If 10 percent of your subscribers open your email when on desktop, but only 5 percent of them open it on mobile, it could be a sign that your emails aren’t as mobile optimized as they should be, or that your subject line isn’t as compelling when truncated.

You may also want to see if a certain operating system tends to yield better metrics for your campaign than others.

14. Clicks by device.

Similarly, you’ll want to evaluate your CTRs per device. A lower CTR on mobile devices could be the result of poorly optimized designs. Your audience may also strongly favor one type of device over another.

15. Domain-based opens and clicks.

Though you may not need to evaluate it as frequently as some of the other metrics on this list, you may want to see if there are any domains with an exceptionally high open rate or click-through rate.

If email addresses from one particular company seem to be enjoying your content more than average, it could represent an important sales opportunity—or could help you learn more about your target demographics.

16. Revenue per subscriber.

Revenue may be hard to calculate, depending on how you’re calculating sales. For example, it’s easy to calculate revenue if you’re only selling products, since they represent a fixed price that can be added up across multiple shopping sessions.

If you’re more service-based, you may have to calculate revenue based on subscriptions, or even based on how many new leads you’ve generated. Isolate your revenue to determine how much has come from your email subscribers, then divide that by the number of subscribers you have.

The higher this number is, the better. You can improve it by refining your email lists with segments, increasing conversion rates and the value of sales, and by committing many other tweaks.

17. Revenue per email.

For a more thorough picture of your campaign results, you’ll also want to calculate revenue per email. Rather than focusing on a per-subscriber value, this metric will help you analyze which of your emails have granted you the best return.

Then, you can analyze the key qualities that enabled those emails to be successful, and replicate them in future drafts.

18. Return on investment (ROI).

Your overall return on investment (ROI) is arguably the most important metric in your campaign, since it provides you an assessment on whether your time and money have been “worth it.”

Start by totaling up the cost side of the equation, noting how much you’ve spent on things like graphic design services, content writing, and any email platforms you’re currently using. Then, evaluate how much revenue your email marketing campaign has brought you for that same period.

Any positive ROI is a good sign for your campaign, but overall, you want to be trending upward (and the higher this climbs, the better).

Email remains the most powerful communication medium in today’s business world, and learning how to master it by scrutinizing the most important email marketing metrics is good strategy for success. Also, be sure not to miss our post on sales email best practices, as well as the top email marketing tools!

Want to learn how many emails you send and receive, and how fast you respond to emails? Or visualize the communication patterns of your team? Then make sure to check out our free trial!