15 Email Marketing KPIs You Should Track

Written by: Chris Donald

Published on: 17-05-2023

Chris is Managing Partner at InboxArmy and has more than 25 years of experience in email marketing

By now, if your business isn’t leveraging email marketing as part of your marketing, you’re missing out on three important things:

  1. Getting more leads/conversions
  2. Building a solid brand presence
  3. Establishing a direct line of communication with your customers.

However, if you’re already a step ahead and have started your campaigns, the next step is to optimize them.

Marketing, in any form, requires a detailed understanding of performance metrics. This helps you spot bottlenecks and opportunities.

If you’re not leveraging email marketing KPIs, you’re losing potential growth opportunities, not to forget conversions. This post will give you a comprehensive outlook of all the necessary email marketing KPIs your business could start measuring and scaling your campaigns.

Let’s get started.

Why Do You Need To Use Email KPIs?

At the beginning, the goal is to gather more subscribers, increase brand awareness, and build a loyal readership.

However, this can’t be achieved merely by putting together an email and sending it to thousands of potential prospects. 

From click-through rate to how many people conclude your email, everything could be measured and calculated to achieve better results in the upcoming campaigns.

These KPIs help you:

  • Identify what’s working for your campaign
  • What type or section of the content is your audience interested in the most
  • Measure the success of your email campaigns and use the same results to optimize your future campaigns.

The effective use of email KPIs can ultimately contribute to a better ROI from your campaigns – not to mention a successful email marketing campaign overall.

15 Email Marketing KPIs Your Business Needs


Even though we have dedicated a long list of KPIs for you to implement, you should also know that email marketing metrics differ from campaign to campaign. It’s not necessary; the metrics you’re using will be used by everyone in your industry.

No matter how much effort you put into creating your email campaigns, it will only be worth it once you can see the results of your efforts and if you’re even close to the goals you’ve set for your campaign.

Lay down your objectives and thoroughly understand what KPIs in the following list would suit your business.

Let’s start.

1. Delivery Destination

The first question your campaigns should answer is – Did my audience receive my email?

Before analyzing your email performance via any metric, the first item on your checklist should be whether your audience can find your emails.

Most times, emails land in different places. For example, you may find emails going into spam, into the promotions or social tab, or worse, into the junk folders of your prospects. 

If your emails are landing anywhere but the primary inbox of a prospect, you need to fix it.

Gmail and other mailing services are getting smarter and better at spam protection. For example, if your emails contain fishy links or any suspicious-looking text, your emails won’t enter your audience’s primary inbox.

Most importantly, if you’re at the initial stages of starting your campaign, chances are that your emails won’t land in the primary inbox. Read more about How To Stop Emails From Going To Promotions

How To Optimize Delivery Destination?

A few practical ways to make sure your emails are landing in primary inboxes are:

  • Warming up your emails – Before starting email marketing campaigns, ensure the email you’re using to send these emails isn’t new or marked as spam by Gmail. An efficient method to do that is by warming up your email. Warming up allows mail delivery systems like Gmail to trust your email address and doesn’t consider it spam. You can use email warmup services like Snov or Warmup Inbox for this.
  • Keeping email format simple – Most emails have a standard format that includes a subject line, a body, and CTA. However, if your campaign requires you to adopt a different email format, like an image-only format, optimizing it for all screen sizes (tabs and smartphones) is vital. An email service like Mailchimp or Beehiiv will automatically optimize your emails for all screens. 
  • Don’t be ‘too’ salesy – Although most emails are sent to generate more sales, making it not too obvious could help. Your emails could have a Call-to-Action for generating sales, but the rest of the email could either be informative, educational, or provide value to your users in some way.

In the image above, you can see a promotional marketing campaign without extra context. An email campaign like this may seem too salesy, and most times, a good portion of your audience is most likely to ignore it.  

How To Calculate The Delivery Rate?

You can calculate the delivery rate of your emails by using the following formula:

Deliverability Rate = (Delivered Emails/Total Emails Sent) x 100

2. Click-through Rate (CTR)

The email click-through rate is an important metric to track. It helps gauge your subject lines’ performance and whether your audience opens them upon receipt. 

Understanding the CTR of your email marketing is more complex than understanding the delivery destination of your emails.

The CTR of your emails is not only limited to the open rate of your emails but also includes whether your audience has clicked on at least one of the links that your emails included.

Having a good CTR is essential to ensure that:

  • your audience is opening your emails,
  • your subject lines are click-worthy,
  • and your audience is most likely to open the emails you send them in the future as well.

How To Optimize CTR?

There are a few effective ways to optimize the CTR of your emails. These include:

  • A compelling subject – The quality of your subject line is directly proportional to how many prospects and customers will open your email. The more effective your subject line is, the more people will open it. You can use TestSubject to check your email’s appearance on mobile devices. 
  • Personalization – Emails that are tailored to your audience on an individual basis can make it more clickable based on the interests and preferences of your audience. 
  • A/B Testing –  Email A/B Testing allows you to send two versions of the same email, with preferably different subject lines. This helps you understand which subject lines draw the most attention, what content works with your audience, and what CTAs are the best.

A/B testing can help you understand the scope of your campaigns side by side.

Not only does it provide a detailed overview of your numbers, but it also helps you discover opportunities to improve your campaigns.

You can leverage A/B testing to understand the following:

  • What subject lines get the best open rates?
  • What types of CTAs are more clickable?
  • What visuals suit your campaign the best?
  • What sections could help retain the attention of your audience?

Most email tools like Beehiiv and MailChimp come with in-built A/B testing tools, which takes the extra technical setup away from your campaigns – ultimately making the job easier for you.

How To Measure The CTR of Your Emails?

You can calculate the click-through rate of your emails by the following formula:

(Total Number of clicks ÷ Total Number of delivered emails) x 100

For example, 

Delivered emails = 10000

Number of clicks = 500

By the formula, your CTR = 500/10000 x 100 = 5% CTR

3. Conversion Rate

Most campaigns are used to get more conversions in your business.  

The conversion rate of your emails is a critical KPI because it gives you an idea of whether your email campaigns can convert your subscribers into customers.

By tracking the it, you’d be able to determine the following:

  • how successful your email campaigns are,
  • what are your areas of improvement,
  • and whether your subscribers are interested in your product/service.

Conversion rate also helps you understand what types of emails work well for your business and those that don’t.

How To Optimize The Conversion Rate?

You can leverage the following actions to improve it:

  • Send out quality content – The more time you spend on the content and making it engaging, the more chances you’ll have of a better conversion rate. Spend time infusing quality content and visual elements into your campaigns. 

Here are tips for writing better email copies:

  1. Use tools like QuillBot or Copy.ai to write compelling content for your emails. 
  2. Write effective subject lines that your audience is interested in.
  3. Use a conversational tone.
  4. Use personalization in emails (including the names of your potential prospects).
  5. Use visuals to build the appeal of your emails.
  • Segment your email list – By distributing your email list based on interests, locations, or other factors, you can personalize your content to make your emails more relevant – thus increasing the chances to boost conversions.
  • Optimize emails for mobile – Most subscribers will likely open your emails on their mobile devices. If your emails need to be better formatted for mobile screens, it will decrease the rate.

How To Calculate The Conversion Rate?

You can calculate the conversion rate of your email campaigns by the following formula:

(Number of conversions ÷ Number of emails delivered) x 100 

4. Hard and Soft Bounce Rate

Bounce Rate is another email marketing metrics that helps you understand the number of failed email deliveries. 

Even though bounce rates aren’t directly entangled with your goals, it still gives you a clear understanding of how many subscribers your emails reach.

There are two types of bounce rates:

Hard Bounce – Refers to the number of emails that return to you as undelivered because the email doesn’t exist. This happens because of misspelt or deleted email addresses. 

Soft Bounce – Refers to the number of emails that are temporarily undeliverable because either the email is too large or the recipient’s email address is temporarily unavailable.

How To Optimize Bounce Rates?

  • Remove hard-bounce addresses – Maintaining a healthy mailing list ensures a healthy spam score index. You can use a list cleaning service like ZeroBounce to do that.
  • Use a reliable ESP – Email Service Providers (or ESP) allow you to push your campaigns. A dedicated application like MailChimp or AWS can improve your email deliverability and reduce the chances of your emails being marked as spam.

5. Unsubscribe Rate

As the term suggests, the unsubscribe rate refers to the percentage of people that unsubscribed from your emails after opening them.

While it’s inevitable that people keep unsubscribing from your emails occasionally, if this rate increases with every campaign you send out, it might be a problem.

Even though it is an important metric, it must still be more effective than your CTR or open rates. This is because most people who want to avoid receiving your emails will either block your email addresses or ignore you altogether.

There are a lot of instances where people will opt out of your emails. 

However, if the rate is growing and you’re collecting complaints over your emails, this may cause concern. Factors such as targeting, message frequency, or product offer might be problematic for a growing unsubscribe rate.

How To Reduce The Unsubscribe Rate?

Drill down into the details of why your audience is unsubscribing frequently. Then, here are some factors that you can consider to optimize your unsubscribe rate:

  • Have a healthy email frequency Too many emails are overwhelming. A healthy email frequency is sending a couple of emails a week. However, if you’re sending daily or even a couple of emails every day, chances are your audience would want to avoid being a part of that in the long run.
  • Offer preferences – Different options for subscribers to adjust their email preferences, including frequency or the type of content they receive, could help. This allows your subscribers to choose what they want to receive from you.

6. Forwarding rate

Forwarding emails and socially sharing your content is a win-win for your campaigns.

The more shares you get, the more organic subscribers you’ll bag. To forward your emails, subscribers click that ‘share’ or ‘forward’ button. 

And even though forwarding is rare in email marketing, measuring your forwarding rate for a successful campaign is still crucial.

Your forward and sharing rate gives you a comprehensive idea about what types of offers or articles your audience considers worthy of sharing with others. This data could be used to tweak your future campaigns. 

How To Optimize The Forwarding Rate?

  • Create sharable content – Creating high-quality and compelling content is something your subscribers will want to share with others. From educational to value-driven content, you can try a myriad of ways to encourage your subscribers to share your content ahead.
  • Have a prominent CTA – Encouraging your audience to share your content could easily be conveyed by having a clear call-to-action. This CTA could be as simple as “Share this email” and should allow your subscribers to share it across other platforms.

How To Calculate The Forwarding Rate?

Here’s how you can calculate the forwarding rate of your campaigns:

(Total clicks on a share/forward button ÷ Total delivered emails) x 100

7. List Growth Rate

So how is your subscribers’ database? Is it growing, stagnant, or declining? 

While considering factors such as deliverability rate, CTR, or conversions, the goal should also be to grow your mailing list.

This helps new people get acquainted with your business. Your campaigns serve a purpose once they are growing organically. Therefore, the list growth rate refers to the pace at which your email list grows.

Keeping track of your lists and segments is a crucial indicator of your success and marketing.

How To Optimize The List Growth Rate?

The formula to calculate your list growth rate is:

(Total new subscribers) – (Number of unsubscribers + spam complaints) ÷ Total number of email addresses on your list x 100

Here are a few ways you can grow your email lists:

  • A lead magnet – Creating a solid lead magnet like an e-book or a free trial of your product or service encourages visitors to sign up for your email list.
  • Use pop-ups – Using email pop-ups and overlays on your website encourages readers to sign up for your email list. You can ensure this by providing valuable content and insights into your content to give readers a reason to hear from you more.
  • Host events – Webinars and other ways of virtual meet are easy to put together and beneficial for your business. You can host these events with a simple CTA asking your attendees to sign up for your email campaigns.

8. Most And Least Engaged Subscribers

The size of your mailing list isn’t as important as knowing how many people on that list regularly interact with your brand.

Having a good understanding of how many subscribers are loyal to your brand and engage with your content frequently is important for your brand. 

Whether it’s a loyalty offer or early access, knowing what percentage of your audience is going to interact with, it can help you tweak your future campaigns as well.

In certain cases, knowing your subscriber interaction rate will also allow you to remove subscribers whose interaction is slowly decreasing. 

How To Optimize Subscriber Interaction Rate?

  • Use dynamic content – You never know how your audience is going to behave to certain promotions and offers, especially when they are tailored to their interest. You can bifurcate your audience and send personalized emails to your least engaged subscribers. 
  • Offer premium access – Having an exclusive membership or tier for your audience based on their interaction can also be an incentive enough for your subscribers to keep up to date with your content.

9. Email ROI

The Return on Investment (or ROI) of your campaigns is a direct indicator of how successful your campaign is.

However, measuring the ROI of your email campaigns isn’t the same for everybody, as every campaign also has different objectives, which usually include the following:

  • Increasing engagement and generating leads
  • Boosting your overall sales and conversions
  • Increasing brand awareness

Measuring your email ROI is crucial to understand the quality of your emails, the engagement, and the effectiveness of your CTAs.

How To Optimize Your Email ROI?

To increase the chances of a better ROI on your email campaigns, you can try the following methods:

  • Personalize your campaigns – By segmenting your mailing list and personalizing your content can help you send emails with tailored content that’s more relevant to your audience. This ensures that most of your audience opens your emails which eventually could lead to conversions as well.
  • Focus on improving all other metrics – This includes your open rate, CTR, deliverability rate, and conversions. All this data accumulated could help you adjust your campaigns accordingly.

How To Calculate Your Email ROI?

Even though brand awareness isn’t a measurable email marketing objective, you still can measure your email ROI by the following formula:

Email ROI = (Revenue gained – Amount invested) ÷ Amount Invested

10. Campaign Performance

Emails are usually a part of a customer journey. They play different roles at different stages in a marketing funnel.

They are either at the start (e.g. brand awareness), at the middle (e.g. sign-up or other types of landing pages), or at the bottom (e.g. booking consultation calls or signing up for a service).

Measuring an entire campaign’s performance makes more sense because it allows you to measure the following:

  • the type of emails your audience interacts the most with,
  • and the kind of content that attracts the most engagement.

Accumulated data from different emails can help you understand what’s working out the best for your campaign. 

How To Optimize Your Campaign Performance?

  • Create distinct email marketing KPIs – This helps you understand the reason behind a campaign’s success or failure. 

As an example, you can use KPIs like measuring the CTR for the entire campaign and comparing it to the CTR for an individual campaign across different campaigns. 

  • Test your content – Since every industry has a distinct type of audience, your emails need to resonate with this audience equally. Try different formats of emails. 

For example, compare the performance of two campaigns – one with more visuals than the other campaigns.

11. Event Lag

How much time does your audience spend between opening your email and taking action – like clicking your CTA?

Firstly, here are few questions you need to ask yourself –

  • What is the audience clicking on?
  • How long does it take them to get there?
  • How long does it take your audience to take the action?

Measuring event lags is an efficient method of understanding the effectiveness of your emails and the different elements involved. These include your subject lines, your email body, and the call-to-action.

How To Reduce Event Lag?

Event lag is an important metric that helps you understand how engaged your audience is with your brand and how quickly they take action upon receiving your emails.

Here’s how you can improve this metric:

  • Use triggered emails – Triggered emails are usually sent upon actions like abandoning a shopping cart, keeping a payment incomplete, or a trial that’s about to end. These emails can encourage users to take action instantly – ultimately reducing the event lag.
  • Leverage social proof – Showcasing testimonials and customer reviews could be an effective motivator for your subscribers to take action. Based on others’ reviews, you could be filling the gap between your potential customer and their need. 

12. Spam Complaint Rate

A spam complaint rate is an indicator of how your audience is interacting with your emails and whether they consider your emails to be spam.

Emails being marked as spam can negatively affect your brand reputation, let alone impact your deliverability rate as well.

Email services like Gmail are notorious for their spam filters. This means that if your spam complaint rate is growing, your emails for your regular audience are also likely to end up in spam folders.

Measuring the spam complaint rate is extremely important to maintain a healthy relationship with your subscribers. The fewer reasons you give them to mark your emails as spam, the lower your spam complaint rate is going to be.

How To Reduce Spam Complaint Rate?

There are a few methods you can use to reduce your spam complaint rate:

  • Use double opt-in A double opt-in method ensures your subscribers not only provide their email addresses to you but also verify their subscription by clicking a verification link in their inboxes. Double opt-in allows you to attract subscribers that are exclusively interested in your business and likely to read your content.
  • Inform your audience what they are subscribing to – Whether it’s a newsletter or a weekly promotional mail, you need to make it clear to your subscribers what you’ll be delivering to their inboxes. This ensures that your audience doesn’t receive irrelevant content or something they don’t remember signing up for.
  • Make unsubscribing easy – If your audience has to toil hard to find that unsubscribe button, chances are they are going to find the easy way out, block your emails, and report you for spam. Make sure that your emails have an unsubscribe button in case any of your subscribers don’t want any more emails from you.

How To Calculate The Spam Complaint Rate?

You can calculate the spam complaint rate of your campaign by the following formula:

(Number of spam complaints ÷ number of sent emails) X 100

13. Subscriber Lifetime Value (SLV)

Much like Customer Lifetime Value, your subscribers also have a similar kind of association.

Measuring SLV will give you insights into how impactful your emails are and how much interaction certain subscribers are showing toward your emails.

You’ll also be able to figure out who are your high-spending customers or frequent purchasers. 

This will help you tailor content to specific segments of your audience and get better results with your email marketing. 

How To Optimize Your Subscriber Lifetime Value?

A healthy SLV means that your emails are effective and have the potential to deliver the results you want them to. And if not, here’s how you can ensure that:

  • Nurture your subscribers – The goal of your campaigns should also include providing value to your subscribers. This includes providing them with valuable resources and insights that they can’t get anywhere else.
  • Offer loyalty programs Loyalty programs are a great way to encourage your audience to stay on the mailing list and benefit from your business from time to time. Offer coupons, discounts, and trials with your loyalty programs to retain your subscribers.
  • Keep your format fresh – To keep your subscribers coming back to opening your emails, update your email format from time to time, including new designs and sections that resonate with your brand, and add appeal to your emails.

14. Email Engagement With Heatmaps

Let’s say you have distributed your email into different sections that include an intro, a body, a few sections in the footer, and some links at the end.

You’d want to know what parts of your email your audience is engaging with the most.

That’s where heatmaps come in.

Email heatmaps can give you a thorough analysis of how your subscribers engage with your content. This provides you with a good idea of what part of your email attracts the most attention from your audience.

Email engagement may seem like an unimportant KPI, but if your engagement isn’t great, it’s a red flag. You’d effectively want to measure the engagement rates and optimize your content to boost engagement and find areas of improvement.

Ultimately, you can use this information to optimize your email content, visuals, CTA, and overall design to drive better engagement to your campaigns.

How To Optimize Your Email Engagement?

  • Use a heatmap – Heatmaps are a great way to understand what part of the email your audience is interacting with the most. Mailchimp is a great heatmap tool that allows you to create heatmaps without even accessing your mailing list. 
  • Use scannable content – Most readers skim your content, especially when your email follows a longer format of content. To help your readers land at the important points, keep your content scannable by using visuals, GIFs, headlines, and bullet points.

15. Number of Replies To An Email

Just like every other KPI on this list, the email response rate is also a direct indicator of how your audience is interacting with your emails.

As soon as you publish a campaign, there’s no reason not to expect responses in the form of:

  • Feedbacks
  • Reviews and Ratings
  • Direct replies from your customers

Email responses aren’t exactly every business’s concern. But as long as your emails are generating replies, your campaigns are a success. 

At the very least, you understand how/why your audience engages with your brand, what they think of your content, and what hurdles stop them from converting.

How To Generate More Replies To Your Emails?

Here are a few ways that can encourage your subscribers to reply more to your emails:

  • Using a conversational tone – Conversations drive more conversations. The more friendly and personalized an email content seems to your subscribers, the more encouraged they’ll feel to give their input.
  • Following up – Follow-ups are like knocking on the door twice when there’s no reply the first time. It’s not necessary, but it’s not bad either. A well-timed follow-up with a different email can increase the chances of getting a response.

How To Measure Email Response Rate?

To do this, use the following formula:

(Number of email responses received / number of successfully delivered emails) x 100

How To Select Email KPIs For Your Business?

Email marketing KPIs can positively impact your email performance and help you achieve the goals that you have set for your campaigns.

However, every campaign is unique – making the priorities of these campaigns different as well.

To choose the most effective marketing KPIs, start by asking yourself the following questions:

  • Why is my business starting an email marketing campaign in the first place? Is it because of conversions? Leads? Or awareness?
  • Who is my target audience? What KPIs and metrics would be the most relevant for them?
  • What metrics are we currently tracking? Do they align with our campaign goals?

Although there are a bunch of questions to ask yourself before you start, the first step should always be to understand whether a certain KPI aligns with the campaign you started (or are about to start).

Selecting the right email KPIs requires a long-term strategy and careful consideration of your overall objectives. 

If you’re new to email marketing, consider the following few actionable steps first:

  • Lay down your objectives – Find out how long your campaigns will last, what metrics would be important, and what KPIs you can implement in all these campaigns to achieve your objectives. If your objective is to drive more revenue, focusing on revenue per email would make more sense.
  • Use a blend of qualitative and quantitative metrics – While quantitative metrics like CTR and open rate give you an idea of how your audience is responding to your content, qualitative metrics like customer feedback and replies also help you determine the quality of your campaigns.
  • Use KPIs that are easy to measure – Most email marketing campaigns would be able to find success in easy-to-measure KPIs. There’s no need to always measure complex data, which is difficult to track accurately, especially if you’re just getting started with email marketing.

Start Measuring Your Email Marketing KPIs

From a broader perspective, email marketing seems as simple as sending a well-formatted email to a bunch of subscribers.

But when you take a closer look at it, you realize that each of these KPIs plays an individual role in how successful your email campaign altogether is.

So do you start implementing every single one of these KPIs in your next email campaign?

Well, not exactly!

The objective of your campaign could very well pivot towards awareness, conversions, or lead collection from time to time. And in each of these goals, different KPIs play an important role in measuring how effective your campaign was.

For example, if your goal is brand awareness, you can use KPIs like CTR, Bounce Rate, and Forwarding Rate.

Paying close attention to your KPIs can help you tweak your campaigns for better results – ultimately bringing you closer to your marketing goals. As long as you know your objectives, KPIs will keep on working out well for your campaigns.

Save the Hassle and Let Experts Hustle (For You) 

Tracking KPIs and staying on top of your email marketing report requires resources. However, getting expertise may require hours of training and head-hunting, and desired results won’t be guaranteed. Leading businesses partner with Inbox Army – one of the most result-driven and reliable email marketing agencies in the US.

Our email campaign management services ensure your best email marketing KPIs are met.

About Author

Chris sent his first email campaign in 1995. He’s worked directly with Fortune 500 companies, retail giants, nonprofits, SMBs and government agencies in all facets of their email marketing and marketing automation programs. He’s also a BIG baseball fan, loves a good steak, and is mildly obsessed with zombie movies. For more information follow him on linkedin

Let Us Help Take You To The Next Level Of Email Marketing

Get in touch to start a conversation.

Get in touch
Multi-ESP Support

We support 50+ ESP vendors. Be it enterprise platforms such as SalesForce and Oracle Marketing Cloud or small and medium sized business platforms such as Mailchimp, Klaviyo, Aweber, and ActiveCampaign, we’ve got you covered.