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January 15, 2018

7 Essential Email Marketing KPIs to Evaluate the Performance of Your Campaigns

Reading time about 12 min

Looking to evaluate the performance of your email marketing campaigns? Establishing your email marketing KPIs is the best way to efficiently measure and compare the performance of different email campaigns. This article will go over the most important email marketing KPIs to help you gauge how well your emails are doing.

Before we start though, what exactly is a KPI?

KPI stands for Key Performance Indicator, and it is defined as a metric that reflects how well your strategy is performing relative to your business goals. Think of them as a grading system for your business.

An important piece of this definition is “relative to your business goals.” It’s impossible to measure performance if you don’t know what you’re trying to achieve.

That means that we have to establish our email marketing goals before we can establish email marketing KPIs. Most email campaigns should at least strive to achieve the following:

  • Get to the inbox (deliverability)
  • Entice as many readers as possible to open
  • Provide value to readers that keeps them coming back for more

In addition to those baseline goals above, your email campaign should also have a specific goal that is linked to a call-to-action within your email. An example of this would be getting subscribers to make a purchase by including a discount code or driving contacts to a specific blog article or eBook on your blog.

Goals that tie to a specific call to action in your emails are called conversion goals — we’ll talk more about these later.

Now that we’ve defined KPIs as well as the main goals for email marketing, let’s examine the top 7 email marketing kpis you should be tracking to gauge your marketing performance.

For each KPI, we’ll discuss:

  • Its definition and how it’s calculated
  • Which goals it measures
  • How you can improve your performance for this metric

Bounce Rate

Formulas for calculating bounce rate:

[1 – (# of emails delivered / # of emails sent)] * 100


(# of bounces / # of emails sent) * 100

Bounce rate helps you evaluate your deliverability by showing you what percent of your campaign failed to be delivered to your contacts’ inboxes. If you’re having trouble with getting your emails to show up in your contacts’ inboxes, make sure you’re following email deliverability best practices.

If you want to be even more granular in evaluating your deliverability and the quality of your contact list, you can also take a look at the rates of the different types of bounces:

  • Hard bounce – Failure to deliver because of a permanent error (usually that the email address doesn’t exist)
  • Soft bounce – Failure to deliver because of a temporary issue (e.g. receiving mail server is down)

In either case, a bounce results in the failure of that contact receiving your email, so it’s important to look at overall bounce rate first.

How to improve email bounce rate

It’s not easy to decrease the soft bounce rate as soft bounces are usually the result of a temporary problem with your client’s inbox.

If you notice that certain clients have frequent soft bounces, the best course of action might be to remove them from your list entirely.

Hard bounces on the other hand, can be remedied through the implementation of:

  • A double optin process, which prevents misspelled addresses from entering your database; and
  • A regular email list cleaning to identify and remove any bad contacts.

To find your bounce rate in Sendinblue, go to the “Statistics” tab on the left menu, then click on the “report” for the campaign that you want to view.

email marketing kpis: bounce rate

Open Rate

Formula for calculating open rate:

(Number of (unique) email opens / Number of emails sent) * 100

Open rate is the front line of engagement. It communicates whether or not your subscribers were interested enough to open your emails and see what you have to say. The higher this number, the better — but you should at least shoot for about 20%.

The open rate also lets you easily evaluate:

  • Email subject line and (to a lesser extent) email preview text – A low open rate might mean that your subject lines are too generic and aren’t sticking out in your contacts’ crowded inboxes.
  • Whether or not you ended up in “spam” – A significantly low open rate can sometimes also signify that your email never made it to your contacts’ primary inbox, but rather was caught in their email provider’s spam filter.

How to improve email open rate

If you want to improve your open rates, you really only have to look at a couple of things:

  • Email subject line
  • Sender name
  • Preview text

Out of those three, the most important is the subject line. This is the first impression that your subscribers see before opening an email. Make sure you optimize your subject line to make your email irresistible to subscribers.

You can also test different sender names to see which one works the best, though as long as subscribers are expecting emails from your business, and the sender name corresponds to that business, this shouldn’t be a big factor.

If you think the problem is related to deliverability (ending up in the spam folder), make sure that you’re avoiding the common mistakes that hurt your sender score.

In Sendinblue, you can find your open rate front and center in any campaign report.

email marketing kpis: open rate

Click Rate

Formula for calculating click rate:

(Number of (unique) clicks on links in your email / Number of emails sent) * 100

Click rate is the best metric you can use to gauge the entire performance of your email campaign. It illustrates very clearly the rate at which your contacts engage with your emails and want to learn more about the content in your messages. This metric hinges on deliverability and open rate, so the higher you can get this number, the better.

Please Note: Click rate will only be important if your email contains one or more links — otherwise, there’s nothing for contacts to click! If your emails have no links, you should instead focus on open rate (or response rate if you’re looking for responses) to evaluate performance.

How to improve click rate

Because click rate requires readers to click on a link inside your email, improving click rate performance requires you to first make sure you have good deliverability and open rates.

Once you have figured those two metrics, improving click rate really boils down to two things:

  • Content of your email and the copy surrounding your CTAs/links
  • Email design

The best way to improve on these factors is to try new ideas, track your results, and see which content and designs have the best engagement.

In Sendinblue reports, click rate can be found right next to open rate.

email marketing kpis: click rate

Click-to-Open Rate

Formula for calculating click-to-open rate:

(Number of unique clicks / Number of unique opens) * 100

Click-to-open rate, or reactivity rate, takes a look at the rate at which people who already opened your email end up clicking through. This metric is perfect for evaluating your calls to action because it’s the raw engagement rate for contacts once they’ve read your message.

If you have a low click-to-open rate, it means that the content of your email or the offer in your call to action was not enticing enough to your readers.

How to improve click-to-open rate

The most effective way to bump up this metric is to increase the overall volume of clicks. To achieve that, make sure your CTAs align with your contacts’ interests. If they see a link to an article that sounds interesting, they’ll want to learn more by clicking through.

If you’re lost on coming up with ideas on how to move the needle, ask yourself these two questions:

  • Is your CTA engaging enough for your audience? If not, try changing up the anchor text or email copy to see if that makes a difference.
  • Does the design of your email make it hard to see the links? Try changing colors and formatting around.

In Sendinblue, click-to-open rate can be found in your campaign report below your open rate information:

email marketing kpis: click-to-open rate

Unsubscribe Rate

Formula for calculating unsubscribe rate:

(Number of contacts who unsubscribed / Number of emails sent) * 100

Why bother with contacts who don’t want to receive your emails anymore? Because your unsubscribe rate can also shed some light on how your customers perceive your email campaigns. It can also tell you if there is a serious problem with the content of your messages or the frequency at which you’re sending them.

The lower your unsubscribe rate, the better. A low number for this measure means that your contacts are generally satisfied with your emails and wish to continue receiving your content. If you notice a sudden increase, take note of any changes you made recently and figure out what went wrong.

How to improve unsubscribe rate

There are several reasons why a user might hit unsubscribe:

  • They’re no longer interested in the content you provide. There’s nothing you can do for these people (short of changing your business that is).
  • They’re receiving too many emails from you. If this is the case, try lowering your frequency or allowing contacts to define their preferred frequency when they sign up.
  • You’re not sending them the content they want. For this, you can either reach out and see what your contacts are looking for, or segment your list and send multiple types of emails to satisfy the different interests of your customers.

You can find you unsubscribe rate at the bottom of your report on the right side.

email marketing kpis: unsubscribe rate

Spam complaint rate

Formula for calculating spam complaint rate:

(Number of spam complaints / Number of emails sent) * 100

You always want your spam complaint rate to be as close to zero as possible because this KPI is a measure of the rate at which your contacts complain to their email providers about your emailing.

This number also has a huge impact on your deliverability. If too many customers start reporting your emails as spam, email providers will begin relegating your emails directly to the spam folder. This will tank all of your engagement metrics since your contacts will no longer be able to see your messages when they’re sent out.

How to improve spam complaint rate

One of the most common reasons for a high spam complaint rate is that contacts are having trouble unsubscribing. Whether it was intentional or not, obscuring the unsubscribe link in your emails is never a good idea. It’s much better to have contacts who are no longer interested in your emails to unsubscribe rather than reporting you as spam. So, make sure to keep that unsubscribe link front and center.

If your unsubscribe link is good to go, the next step you should take is to clean your email list and remove any contacts that are no longer engaged. This will help you keep only your most high quality contacts in your list, ensuring the best engagement rates.

To find spam complaint rate in Sendinblue, visit your campaign’s report page and scroll to the bottom:

email marketing kpis: spam complaint rate

Conversion Rate

Formula for calculating conversion rate:

(Number of people who completed the desired objective / Number of emails sent) * 100

Whenever you have a specific goal for users to accomplish after opening your email, conversion rate is going to be an essential piece of your marketing report. This conversion goal could be a purchase, referral, visit a specific page, or something else entirely — it all depends on your business.

Conversion rate will measure the rate at which your contacts accomplished the task that you wanted from them, making it a true gauge of how effective your emails are. It’s the only KPI that you won’t find in your Sendinblue reports because it depends on the specific goal that you have for each email campaign.

How to improve conversion rate

Because conversion rate depends on your specific campaign, here are some more general tips that can help your overall email performance:

  • Don’t lie to contacts – Few things are more frustrating than clicking through a link only to find that your expectations were completely different than the real content on the page. Don’t disappoint your contacts with hyperbole or false claims — be real instead.
  • Provide value – Make sure that whatever you are offering (content, products, discounts, etc.) or attempting to get your contacts to do (make a purchase, sign up for something) is something that actually provides them with value. Otherwise, they will be upset that you wasted their time.


Now that you’re armed with these email marketing KPIs, you’re ready to start analyzing the performance of your campaigns and keep optimizing them for better engagement.

Do you have other KPIs that are a more effective gauge of email marketing performance? Let us know in the comments below!

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