Top 10 KPI for email marketing

The Email Marketers
December 22, 2021

Top 10 KPI For Email Marketing

Email Marketing: How To Keep Track

Hallelujah! You've seen the light and are now fully on board with email marketing.

You've educated yourself on how valuable email marketing is. And if you haven't, here's a crash course: 60% of email marketers have received significant ROI due to investment in email marketing, according to a study by Marketing Sherpa.

Email Marketing works for any type of product or business. The investment cost is relatively low, and the potential for profit is so high: so much to gain, so little to lose.

But it's not quiiite as simple as it may seem. Email marketing can do wonders for your sales, but, and this is a big BUT, it must be done correctly to succeed. So you're going to need a way to know how to ensure you're nailing those email marketing efforts.

We've already posted about different tactics for email marketing campaigns, such as segmentation, and the possibility of outsourcing your email marketing efforts to an email marketing agency.

So whether you end up DIY-ing your email marketing campaigns or outsourcing, the question remains the same: how do I know if this is working?

This is where Email Marketing KPIs come into play. In this blog, we'll give you the full rundown on the most oft-used KPIs. You'll want to keep these guys in mind as you assess your own email marketing strategy and campaigns.

Preview Time

Because we're not about stringing you along on this blog, take a sneak peek at the 10 Email Marketing KPIs we'll be examining today:

  • Bounce Rate
  • Click-Through Rate
  • Click To Open Rate or Open Rate
  • Open By Device
  • Conversion Rate
  • Email Forwarding Sharing Rate
  • Unsubscribe Rate
  • Spam Complaint Rate
  • List Growth Rate
  • ROI

What Are Email Marketing KPIs?

Let's back up a step. There's an elephant in the room!

You might be asking yourself, what IS an email marketing KPI? In fact, you may not know WHAT a KPI is, let alone an email marketing one.

Don't blush! There are no stupid questions :) Only not-so-cool people who make you feel bashful about asking your questions. And that's not my style.

What's a KPI?

KPI stands for key performance indicators. In any aspect of business, you will want to measure how successful it is. So you choose certain indicators (or metrics) and rate them--the better they do, the higher the KPI score.

Silly Example Time

Say you are a frozen yogurt maker and store owner. You just created a new flavor, Raspberry Lemon Swirl.

You want to know how well that flavor is doing. So you decide on a few KPIs. They might be:

  • How many customers order the flavor after receiving a sample?
  • How many repeat customers of the flavor are there?
  • And how many customers would actually recommend the flavor?

Reasonable questions to ask, no?

The higher the number here, the higher the KPI score. In other words, the MORE people order the flavor, recommend it, and come back for more, the better!

You can compare this flavor against other flavors as well, in order to see if you want to keep Raspberry Swirl on offer. In this way, your KPI score for Raspberry Swirl will let you know if the flavor is working, and if it's worth keeping.

Is Raspberry Swirl Worth Keeping? Looks like it!

Finding YOUR Email Marketing Metrics

You're probably thinking about ice cream at this point, but let's stay on track.

(Don't worry, you won't be using the Raspberry Swirl KPIs for your email marketing campaigns.)

You'll be using completely different email marketing metrics. There are actually quite a few measurements that can come into play, and at the end of the day, it will be up to you and your business to decide which metrics you will use.

Here, we will focus on 10 KPIs we consider the most pertinent when tracking your campaigns.

But First A Little Intro: The Email Marketing Funnel

You can think of your email campaigns as following a funnel of sorts:

  • The wide top: You send a whole bunch of emails out
  • The next, slightly narrower layer: Many, but not all, people receive your email.
  • The even smaller, lower layer: Of those that receive the email many, but not all, open them, and of those fewer answer your call to action and click your link.
  • Tip of the funnel: From there, some, but not all, buy your product or service.
  • Unfortunately, some folks actually unsubscribe or even complain about your emails!
  • Fortunately, some folks love your emails so much that they forward them and your email subscribers list grows!

And there you have it! There's a rough sketch of your email marketing campaign funnel and your KPIs: Email Bounce Rate and Emails Delivered, Click Through Rate, Click To Open Rate, Conversion Rate, Email Sharing aka Email Forwarding, Unsubscribe Rate, Spam Complaint Rate, and List Growth Rate.

Buckle in as we over these email marketing KPIs in detail. Yes, there will be math involved. No, it will not be hard or scary.

The 10 Greatest Email Marketing KPI's

Email Bounce Rate aka Emails Delivered

Having a big email list is great! But just because you have a nice big list, don't assume you can just sit back and watch the conversions roll in. A list is only as good as how active and engaged the email recipients are.

And before engagement even comes into play, the truth is not all those emails actually hit the inbox. A number of emails bounce! The number of emails sent is not a useful metric, rather the number of emails delivered is.

It goes to follow that there will be some emails that are not delivered. They bounce! The Bounce Rate is the percentage of emails sent that did not reach the email recipient's inbox.

The Calculation

(Total number of bounced emails ÷ Number of emails sent) x 100. Basically, it's the number of emails delivered. It can also be seen as the inbox placement rate.

Note: you want your bounce rate to be pretty low, which will mean your inbox placement rate is high.

Types Of Bounces

There are various reasons for a bounce, and there are a couple of types of bounces to consider as you check out your bounce rate.

Hard Bounces

A non-existent email address, closed email accounts, or invalid email addresses result in hard bounces, which are emails that will never be delivered.

Internet service providers (ISPs) use bounce rates to determine an email sender's reputation. Therefore, remove hard bounce addresses from your email list via a tool like to improve your reputation.

(More on sender reputation below!)

Soft Bounces

With soft bounces, a valid email address is temporarily unavailable to receive emails.

Reasons might include a full inbox or a problem with the recipient's email service provider. Re-sending your email message to soft bounces may help, or the recipient's server might hold these emails for delivery once the problem has been resolved.

Sender Performance Score

If you have a poor "sender reputation score," it will mean many of your emails will be rejected. So what is the sender reputation score?

An Internet Service Provider (ISP) or an email service provider (ESP) assigns an email sender a score. This score is determined on a scale of 1 to 100. The higher your score, the more likely it is that your message will be delivered to the recipient's inbox, and the higher your inbox placement rate.

Your bounce rate can become a downward spiral pretty easily, so using it as a KPI is a vital indicator of whether you have that all-important good reputation with service providers.

If you find your bounce rate is high, you'll want to take a few steps to improve it. Clean up your email list and purge inactive subscribers, work on your sender performance score, and retry emails that seem to be valid but didn't get through for various reasons.

The goal is to get that bounce rate low so that the number of emails delivered is high!

A little more info on Sender Scores

Click-Through Rate (CTR)

Ok! Say you got that email through--it didn't bounce. Now, did your customer actually open the email? And did they respond to your call to action?

This is your Click Through Rate (CTR), or the percentage of email recipients who clicked on your email link or links.

The calculation

(Total clicks ÷ Number of emails delivered) x 100

Why CTR Matters

Any email marketer will tell you, the click-through rate is one of the most important email metrics. Why? The click through rate is one of the main goals of email marketing.

You get those emails delivered so that your email clients click on your link and hopefully complete the intended action--this increases your revenue per delivered email!

With the click through rate, email marketing performance can be tracked on a daily basis--making it one of the more important metrics.

Additionally, by tracking how your CTR changes, you can glean information as to how well your email marketing is going and how your call-to-action metrics are looking.

(Side note: For A/B tests, CTR is a common metric to use, as these tests are often designed to find new ways to increase the number of clicks in your emails.)

You can tell that your email recipients are reading and responding to the content if they have a high click through rates. The click-through rate demonstrates that your copy resonates with your email client--and these are the people who you definitely want to keep engaged and active!

Open Rate

Okay, so there's a bit of controversy around this metric, but we still feel it's good to keep an eye on. The Open Rate is simply the number of email recipients who actually open your email.

This can be a good indication as to whether your email subject line (and to a lesser extent the preview text) resonates.

After all, people usually only click open an email if the email subject line interests them and they want to read more. So a high open rate can tell you if your subject line strategy is working. It can also tell you whether you're landing in an inbox that reduces engagement such as spam or promotion.

The Controversy: Were Those Emails Delivered? Like, For Real?

HOWEVER, open rates can be deceiving. Hence the controversy.

There's little doubt that a high click-through rate (CTR) is a stronger metric--after all you wrote the email so that the customer would click the link and hopefully buy your product (conversion rate, but more on that shortly!).

But with open rates, other factors can come into play and muddy the metric. For instance, some of your recipients may open your emails even if they are in the junk folder. In addition, some inbox providers, such as Hotmail, may open your emails without your permission. Even worse, with iOS 15 open rates for Apple users are completely overinflated.

The truth of the matter is that the open rate is a misleading metric for a number of reasons. For instance, if the recipient receives images embedded in an email, it is counted as opened, but many of your email recipients have image-blocking enabled. Therefore, when someone opens an email, it doesn't count towards your open rate, making this an unreliable metric.

But Not A Total Waste!

BUT, don't throw it away all together!

It can still give you information about your subject lines, and comparing your Open Rate to your CTR can potentially give you an idea about what email addresses are definitely "healthy" and which might need some investigating OR those recipients that need to be segmented into a new mail marketing campaign.

Open By Device

Welcome to 2021 as we head into 2022. We can't just look at the simple open rate. No, we have to look at where that open rate came from.

Enter the Open By Device KPI. It's no longer good enough to know that your open rate was such and such a number, you have to know if the email was opened on a laptop, desktop, phone, or another device.

So many ways to open one little email
Um, Why Does This Even Matter?

You might be asking yourself, ok, so my subscriber opened my email on their phone. What difference does that make?

The difference is in design. So much about marketing is what catches the eye, am I right?

Stay with us here: once you know what device most subscribers are using to read your emails, you can go about optimizing your emails and CTA placement for different devices.

The Open By Device metric will also potentially affect your subject line and preview text choices.

You can use email marketing software to track this metric.

Conversion Rate

A high conversion rate is the main goal of a successful email marketing campaign.

The conversion rate is the number of subscribers who opened your email, clicked your link or call to action, and completed your desired action (usually that means they purchased your product).

The calculation

(Number of people who completed the desired action ÷ Number of total delivered emails) x 100.

The Big Cheese Of Email Marketing KPIs

Is this one of the important email marketing KPIs? You betcha.

This is where the profits are. You want this percentage to be high. The higher this is, the higher will be your revenue per subscriber.

So how do you get your conversion rate up? Well, it actually should be part of your initial strategy. Your email's call-to-action and your overall goal should be directly linked to the definition of a "conversion."

The conversion rate is an important metric for determining how well you're meeting your objectives. The conversion rate tells you A LOT about how well your email marketing campaign is doing.

Email Sharing/Forwarding Rate

How do you get in touch with new potential customers? One of those tricky questions that can cause business owners and marketers to break into a cold sweat.

But don't panic! There's good news! You have a tool at your disposal that you may have not thought about yet...

Your Database

You already have a database of people who have signed up for your email list, right? Try leveraging the contacts you already have.

You can't expect new customers to come to you if you only focus on converting your current ones. Track how many new subscribers you accumulate by encouraging your subscribers to forward your email if they find the content valuable.

Free Marketing, Sign Me Up!

The amount of your subscribers who take the action of forwarding or sharing your emails is your Email Forwarding/Sharing Rate. This is another KPI you want to be high. It's kinda like free marketing! Amen! Give me more, right?

There's nothing like word of mouth. Monitor your sharing rates to discover the content most often shared/forwarded. Then, use this information to plan future email campaigns.

You could even make a special page for this very purpose, like in the example below.

Email Forwarding Template from The Kitchen

Unsubscribe Rate

The deal is, you NEED to have an unsubscribe link as part of your campaign. It's the law, after all, and it's just the polite thing to do.

Subscribers cannot feel there's no way out of receiving them, if they aren't into your campaigns anymore, for whatever reason. So, even though you may not want to include it, put that unsubscribe link in!

Your unsubscribe rate is the the percentage of your subscribers who opt out of your email campaign.

The Calculation

The number of unsubscribes ÷ the number of emails delivered.

Reasons Your Unsubscribe Rate May Be Rising

Now, it's important to keep track of your unsubscribe rate, because it gives you an idea of how well your emails are landing with your subscribers.

Do you provide relevant content? If not, then your email client will unsubscribe!

The unsubscribe rate can tell you if you are sending perhaps too many emails (letting you know if your email frequency rate is working for your email campaigns).

You'll want to keep this rate low. Generally, you want to be ADDING more subscribers (your list growth rate--more to come!) than SUBTRACTING. And if it's creeping up and you are getting quite a few unsubscribes, then your new task will be re-engaging customers.

Silver Lining Time

One little silver lining, though: when you look at the unsubscribe rate, remember, as subscribers unsubscribe, it will actually probably improve your conversion rate and your open rate and keep your list active and healthy!

Hey, there's always a bright side in email marketing :)

Spam Complaint Rate

This is one of those tricky KPIs. You don't want this one to even be around! Spam complaints are the boogeyman of email marketing! Stay away from the spam folder at all costs!

The Bad Domino Effect

Spam complaints are like a domino (a bad domino) set into motion. At first glance, it appears that your email has been flagged as spam by your recipients. No big deal, right? So what, you may be saying.

But think again! A spam complaint is a big deal because it means that email recipients are, in fact, actually complaining to their email service provider.

Email deliverability can suffer as a result of this, and your sender reputation is adversely affected.

What To Do If Spam Complaints Are High

So, if an increasing number of people mark your emails as spam, you may want to reconsider your email marketing strategy.

It may be time to redesign how you build your list, your content, the offers you give--give your email campaign an overhaul.

But don't worry, with a bit of elbow grease and perhaps some outsourcing, you can get the unsubscribe rate lower.

Don't beat yourself up too much if your number looks high: it's becoming more and more common for email providers to bypass the inbox and directly send your messages to the junk folder. As a result, your metrics of engagement are impacted.

Remember, there are no "bad," metrics, only data. Once you have your data that your spam complaints are high, then it's time to hand it to your marketing specialists!

Being inventive on how to keep subscribers engaged is what the email marketer does, and, if it's just a tech issue, there's always a way to figure it out. This is where having an expert implementation team and/or an ESP with good customer service can be a lifesaver!

List Growth Rate

If you want to expand your target audience, you should focus on increasing your subscriber list. This brings about more potential buyers or customers! With a growing list, the number of emails sent adds up, and the potential revenue per campaign increases.

The list growth rate is, in simple terms, how many new subscribers you are adding to your email list.

The Calculation:

 ({(Number of new subscribers) minus (opt-outs) minus (invalids and spam complaints)} ÷ Total number of emails addresses on your list) x 100.

Humble, But One Of The Notable Email Marketing KPIs

That's a long calculation for such a simple email marketing metric!

But this seemingly-humble email marketing metric tells you whether or not you're making progress. You know you can keep doing what you're doing if your email list is growing. Is it shrinking? You may want to look into what's causing this--re-strategize and change up your email campaign.

Shrinkage Happens

FYI, because it's our job to give you a valuable insight or two, is, shrinkage is a thing.

Shrinkage happens, and it's natural. Consumers' habits and tastes will change and they will opt out of your email campaigns. That's why keeping a healthy list growth rate is important. Keep replenishing what is lost, and your sales will stay consistent.

Plan for future growth--you know that there will likely be future shrinkage.

The Double Opt-In Technique

One way to ensure that not only your list growth rate is high and that you turn existing leads into active subscribers, but that your new subscribers will actually be good quality subscribers, is using the double opt-in.

With the double opt-in, new subscribers are choosing for SURE that they want to receive your email marketing campaigns! With this technique, you might secure an email address in a contact form, but then ask that they click to fully subscribe in the welcome email. This can help remove bad email addresses as well.

Double Opt-In Example from Chipotle

That being said, for most brands we don't recommend a double opt-in, if the source of your traffic is good.


And here's where the rubber meets the road!

ROI is a REALLY valuable insight into your campaign performance! Firstly, it's kinda the OG goal of all marketing, both email marketing and all other, in our view lesser, forms ;)

ROI is your return on investment. Did the investment you made in email marketing pay off? Did you generate revenue per subscriber (aka the target of your email marketing efforts)?

ROI is the amount of profit made after subtracting your initial investment.

The Calculation

 [(money in additional sales made minus money invested in the campaign) ÷ money invested in the campaign] x 100.

Did Your Investment Pay Off?

The ROI metric tells you if your investment is worth it. Should you even continue email marketing? This number is your answer.

How many conversions did you get from email marketing? Did this translate to revenue and money?

If you can demonstrate the value of email marketing (using email metrics of course!) as a channel that drives real, measurable results, and more revenue per subscriber, then email marketing is your jam.

Start Tracking Your Email Marketing KPIs And Your Campaign Performance

So there it is. A handy guide to 9 Email Marketing KPIs we feel are important to use.

Keeping track of these key metrics will undoubtably give you valuable data about the general success of your email marketing, and provide insight into specifics.

Dig In!

Now you have all your information, it's time to sort through it and take action!

Is your open rate low? Perhaps you need more compelling subject lines.

How many subscribers clicked your call to action? Not many? Well, then you might need stronger calls to action!

Are unsubscribe rates rising? Could be time for a hard look at your email strategy.

What about conversion rates? Are these high? Well, then, you're doing something right!

Email Analytics Translate To More Revenue Per Dollar Invested

These email analytics will be your guiding light as you foray into email marketing. They provide customer data and help you make adjustments over time.

As you consider these important metrics, you'll be on your way to building an evermore honed and effective email marketing campaign.

And, you know what a honed campaign means, right? More sales, more ROI, and more profit!

Congrats and Final Takeaways

Congrats! You just finished The Email Marketers KPIs 101 course.

When it comes to determining the success of an email marketing strategy, email marketing KPIs are your righthand person. You'll find you can adjust your strategy based on these email analytics.

The most successful marketing strategies are constantly adapting--think of good marketing as an example of Darwinism!

Adapt or perish.

These KPIs will affect every aspect of your campaign and your overall marketing strategy, from Subject Line to Content to Design to Tech Issues.

Now, there ARE other KPIs that get talked about, but for now, you have a primer on where to start, and these 10 make almost every list you'll find out there.