What Are Email Marketing KPIs and How to Optimize Them

At MageMail, we extol the benefits of email marketing. There’s no doubt you should be using it to drive revenue to your business, but how do you know if it’s working?

In order to measure the success of your email marketing strategy, you need to focus on the key performance indicators (KPIs). If you’re not keeping an eye on those KPIs then it’s likely you’re not making the most out of your emails.

It can also be tempting to obsessively monitor all the data, but this will be overwhelming and lead to insufficient focus. Instead, follow this guide and zone in on the KPIs that matter.

1. Deliverability

Depending on who you talk to, the definition of deliverability varies. At MageMail, we like to keep it simple. When we talk about deliverability, we are talking about whether or not your emails are making it into the recipients’ inbox.

One of the first steps is navigating through the spam filter.

How to Avoid the Spam Folder:

We have talked about the risk of falling into the spam folder in the past. Did you know 21% of permission based emails never make it into the inbox? So, simply ensuring you have a clean email list alone will not help. There’s no “official” set of rules on how to get through the spam filter, but you should take the following steps to minimize the risk:

  • Relevant, high-quality content: Give your subscribers the emails they signed up to. Ensure the content is engaging and useful.
  • Accurate subject lines: Don’t overhype your subject line. Instead, use it as a short, snappy introduction to the content of your email. If it’s misleading, your open-rate will plummet and alert the spam filter.
  • Check your IP address: If one business or person has sent spam emails from the same IP address, then you will be affected too. There are ways of checking this and resolving if there’s an issue.
  • Correct formatting and coding: Content copied directly from Microsoft Word or poor image files can trigger spam filters. Take the time to ensure all the coding is correct, particularly with HTML emails.
  • Subscribers who have signed up: Everyone you send an email to should sign up directly through your website or app.
  • Include a physical address and unsubscribe link: Not only is this good practice, it’s also the law.

Once you have taken these measures, you should see a healthier deliverability rate.

Bounce Rate

If you are still experiencing issues, it’s time to look at your bounce rate. In The Definitive Guide to Email List Cleaning post, we looked at the two types:

  • Hard bounce: Means there’s a permanent reason the message cannot be delivered. This could include:
    • Email address does not exist or been deleted
    • Domain address does not exist
    • Recipient’s email server has completely blocked delivery
  • Soft bounce: This indicates there is a temporary reason for emails not getting through, including:
    • Inbox is too full
    • Email server is temporarily down or offline
    • Email message is too large

A reputable email service provider (ESP) will clearly indicate the types of bounce in its post-delivery report. It will then be up to you to take action.

With hard bounces, you should delete those email addresses right away. They will never get your emails and have a negative impact on your sender rank.

For email addresses that have indicated a soft bounce, you just need to give them another chance. Consider the size of your message and reduce it if you can. Another reason could be that person is on vacation or simply doesn’t look at their emails that often.

If the email address continues to be unopened or indicate a soft bounce after three months, it’s time to remove it from the list.

Deliverability – Be Proactive

In a sense, this is the most important metric of all. If the email doesn’t make it to the inbox at all, then what’s the point of sending emails?

Fortunately, there is a lot you can do to ensure the vast majority of emails get delivered. Ensure your subscribers have directly signed up to receive your emails, keep the content relevant, and follow good practice. You should always closely monitor the bounce rate and stay on top of your email list.

2. Open Rate

There’s some debate within the industry whether open rate is an important KPI. We believe it’s a good indicator of how engaged your subscribers are with your brand.

After all, a high open rate is better than a low one any day.

However, we do need to look more deeply. Open rate statistics can be misleading because an email is only “opened” when the subscriber receives the images embedded. Since most email clients automatically block images, some of those emails will not be counted in the open rate.

Continue to bear this in mind and use the open rate comparatively with the other metrics, then it can be a good indicator of your email performance.

Open rates vary across the different industries, but around 18-20% shows you’re doing well.

Open Rates – It’s all in the subject line (and preview)

We have already covered this extensively, but again one of the most effective ways of boosting your open rate is to focus on the subject line. One study suggests 35% of email recipients decide to open emails based on the subject line alone.

So, how to make yours stand out? Keep it short and simple, ideally less than 20 characters. This is the limit before subject lines get cut off in mobile devices.

Use humor, intrigue, and excitement to get subscribers to click open your emails. However, it’s critical you do not overhype as it will lead to disappointment and they will not open in the future. Most importantly, keep it relevant to the content of the email.

NextDraft Subject Lines

(Source: Author’s screenshot)

NextDraft is a daily news service from Dave Pell. Famous for its no-nonsense, “real” news, the subject lines reflect the brand and content of the email. Each one is short, succinct, and direct.

The fact is this is what the subscribers have come to expect and can’t help but click open.

The bottom line is to consistently deliver content your subscribers want to read at regular intervals. If you’re doing it right, with strong subject lines, then the open rate will look after itself.

3. Click-Through Rate

This is a very simple metric to look out for. It measures how many subscribers clicked through from your email after opening it. A high click-through rate means you are generating enticing, relevant content that engages with your audience.

For e-commerce, the average click-through rate is 2.32%. Yet there’s much you can do to perform significantly better.

The key is to craft a well-designed email, with a clear message and call-to-action (CTA). You also need to provide enough information to get your subscribers interested while making them click through to find out more.

SecretEscapes CTR

(Source: Author’s screenshot)

Travel brand, Secret Escapes uses images to grab the attention of its subscribers. Who can resist the sunset over the Croatian Rivera?

There’s the mention of a special deal and the urgency factor. However, to find out how much it is, the recipient must click through.

It’s a smart case study in email design.

Click-Through Rate – Be Enticing, Engaging, and Relevant

The email open rate is the metric that measures the effectiveness of the first impression. The click-through rate indicates how persuasive the content of your email is. Focus on one main message and entice the reader to click on the links.

Give away just enough information so the subscribers know what your email is about. Utilize smart email design to make the content easy to follow and enable the links to stand out.

4. Conversion Rate

The conversion rate is not necessarily a measure of how many people bought a product from the email. Rather, it shows how many people have taken the action the email asked them to take.

Like click-through rates, its success depends on enticing subscribers to carry out the intended action. The message needs to be clear and focused.

Netflix CTA

(Source: Author’s screenshot)

Netflix frequently send updates on new programs to its subscribers. In this case, the recipient clicking on the red “Play” call-to-action and watching Queer Eye would count as a conversion. This is the key difference between click-through and a conversion.

In order to complete a conversion, you need to think about where the subscriber goes once they have clicked the main CTA. Netflix nailed it with this email. Once you hit “Play,” you are taken straight to the first episode of Queer Eye:

Netflix landing page

(Source: Netflix.com)

Netflix makes it as easy as possible for subscribers to complete the action the email wants them to take. With just one click, you could be watching one of their top programs.

You can apply the same “one-click” principle to your email marketing strategy.

Conversion Rates – Be focused and direct

As we can see with Netflix, you can convert subscribers using minimal content. The design of the whole email, even after clicking that “Play” button, creates a seamless journey for the customer to follow.

Other tips is to utilize automated emails such as abandoned carts, welcome emails, or winback campaigns. MageMail offers all these services and has helped clients recover over $60 million with automated emails alone.

Here’s a good example from one of our clients, PenFactory:

pasted image 0

(Source: Author’s Screenshot)

The email, once again, is short and focused. The friendly, helpful tone is designed to put the potential customer with comfort.

5. Open Rate by Device

Not too many companies track this KPI, but we decided to throw it in since the number of emails opened on mobile devices has grown by 180% in three years.

This figure alone makes it important for your business to monitor how your emails are being opened. It can have a big influence in design and lead to a focus on mobile responsive emails.

Open Rate by Device – Monitor and respond

As a business, you need to keep with the current trends. While email marketing has stood the test of time, the way we interact with emails is changing. It’s no longer enough to simply do a preview email on your PC and send it out.

You need to test across multiple devices and see how your subscribers respond. A/B testing (or split-testing) is one of the most effective ways of doing this. It allows you to compare results from emails with different designs and spot strengths and weaknesses in each.

Monitor the post-delivery analytics and identify trends. If your mobile open rate is low, then it could be down to poor design.

Don’t forget that MageMail already offers each of these features to allow you to analyze the data and test your email campaigns.


The first four KPIs are the ones to focus on for the complete picture of your email marketing performance. It may be less than you think, but there are plenty of details that go into each indicator.

For delivery, there’s a whole host of factors at play – poor email addresses, oversized emails, and inactive subscribers. At the end of the day, you need to do whatever it takes to effectively get your email into the intended inboxes, even if it means cleaning it up

Then it’s time to look at the open rate. Ensure the subject lines are relevant and enticing. Do not treat them as an afterthought.

The click-through rate is all about the content within the email and placing the CTAs in the right places.

Conversions are the holy grail of email marketing. And Netflix absolutely nailed it with its focused email design and customer journey, straight from the inbox into the show.

Each of these factors combine to help you identify the strengths and weaknesses of your email marketing strategy.

Finally, we covered open rate by device to help you shape your strategy for the future, as an increasing number of people are reading emails on mobile.

  • Sapan Gupta

    That’s a great read! I totally agree with checking if the business emails are actually landing into the recipients email inbox or not. Much of the time it lands on the spam folder, and this is no good sign for any business. This does in fact make it extremely crucial to check for the factors that cause the emails to land in the spam folder.

    I have heard a lot about KPI but never really got a chance to dig into what it is exactly. Would really like to know more about that! Other than that, great job, Amanda!

Leave a Comment