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8 essential email marketing KPIs + 10 pro metrics to advance your strategy

Amy Elliott Amy Elliott
· 26 min read · September 14th, 2022
Successful email marketing takes considerable time, effort and money, which is why it’s super important to track the right email marketing KPIs to better understand your return on investment.

It’s nice to know as much as possible about how your campaigns are performing, but keeping up with every Key Performance Indicator (KPI) is a lot. Not to mention, it can be a distraction to monitor too many KPIs when it comes to optimizing your strategy. 

Knowing which email marketing KPIs to focus on first requires that you set specific goals. Once you’ve pinned down what you want to achieve, it’s much easier to identify which email performance metrics are going to help get you there. 

In this article, we’re sharing the essential email KPIs to track and how to improve them, as well as additional KPIs that can help you take your strategy to the next level. 

What are email marketing KPIs?

Email marketing KPIs are the metrics that allow you to measure the performance of a campaign. They help senders to understand how subscribers react to different elements of your emails and therefore, how successful those elements are or where campaigns can be improved. 

For example, open rate can help you to determine the success of your email subject line while Click Through Rate (CTR) can help you to gauge the effectiveness of your call to action (CTA). 

Why is tracking email KPIs important?

Email marketing is an ongoing process that needs constant evaluation and adjustments to optimize your campaigns and account for changing technologies, trends, seasons and events. There is no set it and forget it approach! 

The purpose of measuring campaign performance is to keep learning and improving. Email marketing KPIs empower businesses to learn more about their audience and improve their campaigns in order to increase their Return On Investment (ROI) and reach their goals. 

"Remember, measuring performance is a health plan, not a post-mortem."

Without tracking email KPI metrics, there is no way to measure whether or not your campaigns are working. There’s no point in spending considerable time and money crafting awesome campaigns only to then not check out how they’ve performed!

8 essential email marketing KPIs to track

To start off with, all email marketers should make themselves familiar with these 8 essential email marketing KPIs and their benchmarks. 

1. Open rate

Email open rate tells you the percentage of emails that were opened out of the total number that was sent. It can be helpful in testing out and evaluating the performance of your subject lines and can also give you a heads up if anything fishy is going on with your subscribers.

Open rates, however, aren’t always completely accurate due to the way that the data is tracked. To track email opens, a tracking pixel is embedded in the email. When the email is opened and the pixel is loaded, it counts as an open in your email marketing software. 

Initiatives like Apple Mail Privacy Protection have made it difficult for Email Service Providers (ESPs) to accurately measure opens. Plus, some subscribers may have disabled images for their inbox, so that no images (including those pesky pixels!) will be loaded. 

That being said, it is something you should monitor, as any drastic changes could indicate an issue with your sending.

Average benchmark across all industries: 27.91%

Graphic with the formula to calculate email open rate.
Check out this guide to learn what the email marketing benchmarks are for your industry.

Top tips to improve your open rate

  • 1

    Clean your email list: Verifying your subscribers will help you to weed out invalid email addresses such as disposable emails, incorrect emails (typos) and emails that will bounce. Removing these invalid email addresses will ensure you send to a better quality list with more opens.

  • 2

    Get creative with subject lines to stand out in the inbox.

  • 3

    Use segmentation so that you only send your subscribers the types of content they want to see.

  • 4

    Get your timing right. Test out sending emails at different times of the day on different days of the week to see when your subscribers are more likely to open your messages.

2. Click-through rate

Email click-through rate is the percentage of emails sent that has resulted in a unique click on one or more links in your email. CTR is an important metric for all email marketers, as it’s a more accurate and reliable email KPI to measure the performance of your messages. It gives a look at how engaged your subscribers as well as how interested they are in the content, offer or promotion you are sending. 

Note: Click-through rate (CTR) is not to be confused with Click to Open Rate (CTOR). While CTR is based on the number of emails sent, CTOR is the number of clicks based on the number of opens.  CTOR: Number of clicks / Number of opens x 100

Average benchmark across all industries: 3.75%

Graphic with the formula to calculate email click-through rate.

Top tips to improve your email CTR

  • 1

    Test, test and test some more with A/B testing. You can try out different CTAs, different copy, different tones of voice and different images.

  • 2

    Make your CTAs stand out. Whether it’s an in-text link or a button, no one is going to click on your link if they can’t see it!

  • 3

    Segment your subscribers by interest and create personalized emails to provide more value. If your subscribers are more interested in what you’re sharing, they’ll be more likely to click.

  • 4

    Create an email design that’s consistent and easy to follow. If you have content all over the place with clashing colors and fonts, it will be hard for subscribers to find what’s relevant to them.

3. Conversion rate

 Email conversion rate is the percentage of recipients who have converted via your email by completing the desired action. Getting conversions is the ultimate goal of any marketing strategy and can be anything from monetary goals (sales) to collecting leads by convincing subscribers to respond to a survey or fill in a form. 

A high conversion rate from your email marketing signals that your subscriber list is of a high quality, and that you’re targeting the right audience with your newsletter. 

Average benchmark across all industries: 15%

Graphic with the formula to calculate email conversion rate.

Top tips to increase your conversion rate

  • 1

    Make it as easy as possible for subscribers to convert. The fewer barriers to conversion, the more likely they are to follow through. Keep forms short and only ask for essential information. Make sure the process to convert is clear with buttons highlighted and important elements placed strategically on the landing page.

  • 2

    Remove any distractions from your landing page such as the main navigation menu, links to articles and anything else that could direct attention away from the main objective.

  • 3

    Highlight your objective and keep things short and sweet. Subscribers should know almost instantly what will happen when they fill in the form, enter, register, download or purchase.

  • 4

    Here’s that magic word again: segmentation. Targeting subscribers with offers and content that’s relevant to them is a surefire way to get more conversions.

4. Bounce rate

Your bounce rate is the percentage of emails that cannot be delivered. There are two types of bounced emails, soft and hard. 

Soft bounces happen when a temporary error occurs, such as a full inbox, a limit on the number of emails the inbox receives, or the mail server being offline. 

Hard bounces occur due to permanent errors such as invalid email addresses, typos or if your IP or domain has been blocked by the receiving mail server. 

It’s important to keep an eye on this email marketing KPI as it gives you an indication of your email list health and sender reputation. Hard bounces can mean that your email list is in need of scrubbing, as well as signaling there might be a more serious issue that has resulted in your IP being blocklisted

Average benchmark across all industries: 0.55%. A bounce rate < 2% is considered good. 

Graphic with the formula to calculate email bounce rate.

Top tips to improve your bounce rate

  • 1

    Scrub that email list! Email verification is the best way to remove invalid and risky email addresses that could result in hard bounces.

  • 2

    Keep it clean—your newsletter, that is. Don’t send anything that could be flagged as spam.

  • 3

    Be a consistent sender. If you go for long periods of no sending and then suddenly send out thousands of emails it can look suspicious to Internet Service Providers (ISPs). Consistency is key.

  • 4

    Enable double opt-in for your subscribers to reduce the number of invalid email sign-ups.

5. Unsubscribe rate

Your unsubscribe rate reflects the number of unsubscribes from your email list. 

It helps you to understand if you're targeting the right audience with your newsletter, but unsubscribe rate is not the most reliable email campaign metric. You can gain better insights by looking at other metrics such as CTR, conversion rate and bounce rate. This is because if a subscriber isn’t interested in your content, they often won’t even open your email, let alone unsubscribe from it. 

Average benchmark across all industries: 0.33%

Graphic with the formula to calculate unsubscribe rate.

Top tips to improve your unsubscribe rate

  • 1

    Play with your email frequency to find the right cadence for your newsletter. Overwhelming subscribers with too many emails can send them running for the unsubscribe button.

  • 2

    Segmentation is your email marketing best friend—don’t be shy! Segmenting your subscribers is the best way to provide personalized content that appeals to the maximum number of people.

  • 3

    Optimize your unsubscribe page by asking unsubscribers if they are sure they want to leave your email list. Go a step further by asking why they want to unsubscribe. You can use this information to improve your strategy.

  • 4

    Use interest groups on your forms to find out what topics subscribers are interested in and how often they would like to receive your newsletter.

6. List growth rate

List growth rate is the rate at which your number of subscribers increases over time. This can help you to understand if your email list building strategy is working well or if it’s time to rethink how you’re collecting subscribers. 

It’s natural that with time, the rate that your email list grows will vary, but it’s a good newsletter KPI metric to follow as it can help you to expand your audience and grow your business. 

Graphic with the formula to calculate email list growth rate.

Top tips to boost your email list growth rate

  • 1

    Use strategically placed sign-up forms on your website. You can include a subscribe form on every page of your site by adding it to the footer.

  • 2

    A/B test your CTAs to find what gets the most sign-ups. You can play with copy, button text and color, imagery and titles.

  • 3

    Encourage fans and followers from other channels to join your email list. This could be customers from your website, social media followers and even in store customers.

  • 4

    Play with pop-ups on your website. Perfectly timed pop-ups can be extremely effective in collecting subscribers—just make sure they don’t interfere with the user experience!

7. Spam complaint rate

Your spam complaint rate indicates the percentage of subscribers that have marked your email as spam. No one wants to see their carefully crafted content receive a spam complaint, but it’s crucial to follow this email marketing KPI in order to maintain your deliverability and sender reputation. Too many spam complaints can result in your IP or domain being blocked and your sender reputation suffering. 

A high spam complaint rate could mean that your subscriber list needs cleaning, either because it’s old or potentially because you have some subscribers who did not consent to receive your emails.

Average benchmark across all industries: < 0.1%

Graphic with the formula to calculate spam complaint rate.

Top tips to improve your spam complaint rate

  • 1

    Keep your subscriber list fresh and clean. The older your email list, the more likely you are to have inactive subscribers—there could even be a few spam traps!

  • 2

    Make it easy for your subscribers to unsubscribe. It might seem counterintuitive but an unsubscribe from your email list is much better than a spam complaint.

  • 3

    Deliver what you promised to your subscribers when they signed up and be consistent. If you need to change your direction at any point, inform your subscribers and let them know they can unsubscribe if they want.

  • 4

    Periodically ask your subscribers to re-opt in to receive your newsletters. If they are interested in what you have to say, they’ll stay subscribed.

8. Overall Return-On-Investment (ROI)

Your email ROI is the overall monetary return you receive on your investment into your email marketing strategy as a whole or individual campaigns. 

Email marketing is one of the most rewarding digital marketing channels in terms of ROI, with the average return-on-investment as high as 3,800%. Not only does ROI help you to evaluate and optimize your email marketing strategy and budget, it can also help you to demonstrate to key decision makers the value of email marketing. 

Average benchmark across all industries: 3,600% or $36 for every $1 spent

Graphic with the formula to calculate email ROI.

Top tips to increase your email marketing ROI

  • 1

    Set clear measurable goals and continuously monitor and improve your strategy based on the relevant email KPIs. Don’t forget to save this guide for reference!

  • 2

    Maintain a healthy sending ecosystem with a focus on email deliverability. If your emails aren’t getting delivered, you’ll be wasting money sending them without any chance of results. Yep, this includes cleaning your email list regularly!

  • 3

    Use email automation to send timely, highly-personalized emails that strike when the iron is hot. The more opportunities you follow up, the more conversions you’ll get.

  • 4

    Ensure your emails are responsive and optimized for mobile. Studies have shown that 85% of mobile users use their smartphone to access email. That’s a huge audience you could be missing out on if your emails aren’t displayed properly for them.

Check out this article on how to maximize your email marketing ROI to learn more. 

Additional email marketing KPIs every pro should know

If you want to really take a deep dive into your email marketing performance, these additional KPIs should be on your radar. These email campaign metrics can help you better understand the health of your email list and sending account, as well as give further insights into subscriber satisfaction. 

1. Inbox placement rate

This deliverability KPI, also known as IPR, is the percentage of emails that reach the inbox of your subscribers rather than their spam folder. 

A low inbox placement rate could indicate that you have a less than stellar domain or sender reputation, either because of your sending infrastructure or because of your sending practices. Your email content could also be to blame—badly formatted emails and spammy content can land you in the junk folder instead of the inbox. 

Graphic with the formula to calculate inbox placement rate.

Top tips to increase your inbox placement rate

  • 1

    Authenticate your email by implementing the SPF and DKIM protocols, and optionally DMARC. This will help Internet Service Providers (ISPs) to verify that you are a legitimate sender.

  • 2

    Clean up your email list and remove subscribers that haven’t engaged with your emails in 90-180 days.

  • 3

    Send only relevant, valuable content to your subscribers so they’ll be more likely to open your emails. Make use of our trusty friend, segmentation, to boost your personalization.

  • 4

    Check your emails for issues before you hit send to avoid any nasty surprises. Look out for spam-like content and check for broken links, images and other technical issues such as invalid HTML validation.

Boost your IPR with MailerCheck

MailerCheck’s Inbox Placement feature tests your email against the inboxes of the most popular ISPs while Email Insights scans your message for technical and content issues.

2. Email list health rates

These email metrics reflect the percentage of subscribers or email recipients in your email list that are valid or invalid. These include:

Valid emails: Woohoo clean, healthy and verified. The higher the number of valid emails the healthier your list.

Catch-all emails: Emails in the catch-all category are risky, as the mail server will accept messages, however, the email address might not belong to a real person. 

Disposable emails: These are temporary emails that people use to sign up for services or offers to avoid getting emails sent to their inbox. You shouldn’t send to disposable email addresses.

Role-based: These are real email addresses, however, they may belong to a department or group of people rather than an individual. 

Syntax-error: Oops, these email addresses are not valid. 

How to calculate email list health rates: An email validation tool such as MailerCheck will scan your email list for errors and return the percentage of each type of email your list contains.

Email health rates including Valid emails 67.8%, Mailbox not found 12.4%, Syntax error 2.2%, Role-based 3.0%, Typo 0.2%, Catch-all 13.9% and Others 0.4%
Average email health rates in a study by MailerCheck based on 33,723 email lists checked.

Top tips to improve your email list health rates

  • 1

    Regularly clean your email list by running it through an email verification tool like MailerCheck at least twice a year. MailerCheck will identify any invalid email addresses (like the ones mentioned above!) so you can remove them from your list.

  • 2

    Implement double opt-in for subscribers so that they verify their email address before being actually added to your email list.

  • 3

    Practice good subscriber acquisition by always getting consent to be added to your email list.

  • 4

    Remove any email addresses that hard bounce from your email list. This will allow you to maintain your list between cleanings!

3. Forwarding rate

The forwarding rate email marketing KPI indicates the percentage of recipients that have forwarded your email. This is a great email marketing metric to understand whether your content resonates with your subscribers, and which types of content they are particularly interested in. 

Average email forwarding rate: 0.02%

Graphic with the formula to calculate email forwarding rate.

Top tips to improve your forwarding rate

  • 1

    Ask subscribers what types of content they want to see from you and create more of it.

  • 2

    Use segmentation to personalize the types of content you send to different groups of subscribers.

  • 3

    Optimize your emails for increased opens and clicks—the higher the engagement, the higher the chance of email forwards.

  • 4

    Keep track of which types of content get the most forwards and use that information to inform your future email marketing campaigns.

5. Revenue Per Email (RPE)

RPE tells you the value of each email that you have sent in a campaign. For example, if a campaign generated $1,000 of revenue and you sent the campaign to 200 subscribers, the revenue per email would be $5.

Graphic with the formula to calculate revenue per email.

Top tips to increase your RPE

  • 1

    Take note of which types of emails generate the most revenue and optimize your campaign based on this. Don’t forget about A/B testing!

  • 2

    Write short, snappy, engaging copy that guides the subscriber towards completing an action or making a purchase.

  • 3

    Make use of email marketing automation to remind customers about the products they were browsing, added to their cart, or that complement a recent purchase.

  • 4

    Use personalization to target customers with products and offers that are significant to them.

6. Subscriber Acquisition Cost (SAC)

Another thing to consider when it comes to the value of your subscribers is how much it costs to acquire them. Subscriber acquisition cost puts on a number on each subscriber in relation to the sales and marketing costs it has taken to sign them up. 

MailerCheck

Top tips on how to improve your SAC

  • 1

    Consider a referral program to enable subscribers to easily recommend your email list to their friends.

  • 2

    Optimize your forms and landing pages for increased sign-ups—make it clear and easy to subscribe.

  • 3

    Test out multiple methods to collect subscribers and then optimize those that work best.

  • 4

    Remember: quality > quantity. When it comes to costs, the instinct is to drive them as low as possible. But with SAC, lower costs can mean more subscribers of a lower quality. Stay focused on attracting high-quality subscribers rather than the best subscriber acquisition cost.

7. Revenue Per Subscriber (RPS)

Revenue per subscriber enables you to track the revenue each subscriber from your email list generates. This is an interesting metric as it allows you to delve into the value of your subscribers. 

Graphic with the formula to calculate revenue per subscriber.

Top tips to increase your revenue per subscriber

  • 1

    Create interest groups and segments to send personalized content to subscribers.

  • 2

    Clean your email list—inactive or invalid subscribers are dead weight. Clean your list to only send to real, engaged subscribers.

  • 3

    Focus on optimizing your campaigns for opens, clicks and conversions to increase sales and revenue.

  • 4

    A/B test CTAs and landing pages to learn what drives the most conversions with your subscribers.

8. Subscriber Lifetime Value (SLV)

You can use the RPS metric to determine your subscriber lifetime value. This can be a little trickier to work out as you’ll first need to work out the average amount of time a subscriber spends on your email list.  

Graphic with the formula to calculate subscriber lifetime value.

Top tips to increase your subscriber lifetime value

  • 1

    Use lead nurturing campaigns to build and strengthen customer relationships and loyalty at every stage of the funnel.

  • 2

    Reward loyalty with special offers, exclusive content and freebies.

  • 3

    Send personalized email campaigns relevant to their needs and interests.

  • 4

    Ask for feedback regularly—find out what your subscribers like and don’t like, and what suggestions they have for improving your content, product or service.

9. Email opt-in conversion rate

Your opt-in conversion rate is the percentage of website visitors that convert by opting in to your email list. It tells you how successful your email list building efforts are so that you can improve landing pages, pop-ups, forms and CTAs. 

Graphic with the formula to calculate email opt-in conversion rate.

Top tips to improve your email opt-in conversion rate

  • 1

    Be clear about what subscribers will get if they sign up and explain the value of your newsletter.

  • 2

    Share a taste of what’s in-store with a gallery of past newsletters and a sneak peek at exclusive content and offers.

  • 3

    Keep testing and improving your opt-in forms, landing pages and CTAs to find what gains the most conversions.

  • 4

    Use incentives such as lead magnets, discounts, freebies, and access to exclusive communities.

10. Mobile open rate

Just like open rate, mobile open rate is the percentage of emails sent that are opened on mobile. Again, it’s not the most reliable email metric due to the reasons mentioned in the open rate section above, but it can tell you whether there are improvements to be made to your emails for mobile users. 

Graphic with the formula to calculate mobile open rate.

Top tips to improve your mobile open rate

  • 1

    Optimize your subject lines by keeping the focus in the first 25-30 characters, as this is what will be visible on most mobile email clients.

  • 2

    Use BIMI (Brand Indicators for Messaging Identification) to make your emails more recognizable in the inbox. BIMI places your logo next to your sender name.

  • 3

    Play with your preheaders—many mobile notifications display an extended number of characters in the preheader so make use of this space! Just remember to include the main point of the preheader at the beginning.

  • 4

    Make your emails responsive and easy to view and read on mobile. If the experience is sucky, your subscribers will be less likely to open your messages in future.

Choose the right email marketing KPIs

There are so many email marketing metrics to consider, but there is no need to take on everything at once! Some email KPIs will be more relevant to you than others, but monitoring those mentioned in this article will allow you to improve your campaigns and keep a watchful eye out for unusual activity. 

By breaking down your email marketing strategy and setting specific goals, you can easily identify which KPIs will help you to measure and optimize each element. Determine which goals are most important to you and focus on those until you’re ready to put more focus elsewhere. 

Which email marketing KPIs are most important to you and your business? Give us your input in the comments below!

Ready to clean up your email list?

Try MailerCheck! The all-in-one email marketing optimization tool with email verification, inbox placement testing, email insights and more.

Amy Elliott
I’m Amy, Content Writer at MailerCheck. As a child, I dreamt about writing a book and practiced by tearing pages from an A4 notepad and binding them with sugar paper. The book is pending but in the meantime, I love taking a deep dive into technical topics and sharing insights on email metrics and deliverability.