Are Your Marketing Emails Effective? These 10 KPIs Will Tell You

Email marketing never works when the mentality is “set it and forget it.” Think of your process like a lab. To figure out what’s working and what needs improvement, you need to always be analysing your results. And the key to proper analysis is having the right email marketing KPIs (key performance indicators).

Identifying the right KPIs always depends on the nature of your business: “Success” varies a lot if you’re selling enterprise software to executive buyers, versus sneakers to anyone who wants them. Plus, the accelerated transition to the digital-first customer has added extra nuance on top of this already complicated process. For example, changes to privacy rules such as Apple’s mail privacy protections have made open rates difficult to accurately track.

However, there are some baseline KPIs that almost every email marketer should be using. Here are 10 email marketing KPIs to help you understand how well your messages are connecting and make adjustments to boost success.

1. Delivery rate

Delivery rate is the percentage of emails delivered. ((Number of sends) — (Number of Bounces)) / (Number of Sends).

Did your intended audience receive your email? This is where everything should start when reviewing your campaigns. If your emails aren’t successfully delivered to inboxes or are going directly to spam, your offers and content, regardless of how compelling, aren’t being received.

2. Click-through rate

The click-through rate is the percentage of clicks once an email is opened. (Unique Clicks) / (Delivered Emails).

Click-through rate (CTR) is the percentage of email recipients who not only opened your email but also clicked on at least one of the links in the email. Marketers can use this to measure the strength of the email’s content, messaging, or offers. Combining this with web conversion (coming later!) can indicate whether your email and web messaging are aligned to create a relevant, consistent, and successful customer journey.

3. Clicks by link/URL

These are unique clicks on a link within a single email or across many emails. They are sometimes tracked by aliases or UTM parameters.

It’s also critical to know what people are clicking on. A high CTR can look nice on the surface, but what if all those clicks are for the unsubscribe button? Or maybe your customers are clicking a link early in the email and not the main call to action you built your campaign around. Tracking clicks by link can help you identify what is grabbing people’s attention and that the flow of your email is working as intended.

4. Event lag

Event lag is the average time that passed between the click and send time.

Okay, so we know if someone has clicked, and what exactly they’re clicking on: But how long did it take for them to get there? Event lag is a great way to measure the effectiveness of your subject lines, preheaders, and the content of the email itself. With this measurement, you can understand if customers are moving quickly to open your emails, or letting them languish in their inboxes.

5. Bounce rate by bounce type

Bounce rate is the percentage of messages rejected by the email client (e.g., Google, Apple). (Bounces) / (Sends).

While delivery rate is one of the key email marketing KPIs, it doesn’t tell the whole story. If your email isn’t reaching your customers’ inboxes, you need to understand why. This could occur for a variety of reasons, such as an invalid email address, a full inbox, a down server, or mail that was simply too large for the recipient’s inbox. Bounces are typically organized into a few categories, including:

• Block. Bounces resulting from a complaint, blocklist, content, URL block, or authentication error.
• Hard. Bounces caused by an unknown domain or user, or syntax error.
• Soft. Bounces resulting from a full or temporarily inactive mailbox, or temporary domain failure.
• Technical. Number of bounces caused by the server, data format, or network error.

It’s important to track emails that have ‘bounced’ — and why — so you can avoid bounces in the future. For example, block bounces could be indicative of mismanagement on the marketer’s end, while soft bounces are typically out of the marketer’s control.

6. Unsubscribe rate and complaint rate

The Unsubscribe rate is the percentage of unsubscribes per deliveries.

The complaint rate is the percentage of complaints per deliveries. A complaint is logged when a subscriber flags the email as spam.

While unsubscribes can be demoralising, there is a lot that can be learned from them. It’s critical to set benchmarks for these. What is your average unsubscribe rate per email? It’s natural that some churn will happen: For example, a company that targets parents with young children will have to continuously scrub and update their lists as those customers’ children outgrow that brand or product.

On the other hand, high unsubscribes and complaints for a specific email, or over a specific time period, are a flashing red flag for change, whether it’s your targeting, frequency, messaging, channel, or product offer. By drilling down into the details of the subject lines and content by segment for each send, you can understand mistakes to avoid in the future.

7. Web traffic and conversions

Web traffic and conversions are the bread and butter of email marketing. Almost every email campaign is leading customers to some sort of web property where a conversion can happen. Yet this is often left untracked, as it requires connecting two data silos: email and web.

This typically calls for adding UTM parameters to email links to easily align data from your email marketing tool with data from your web analytics tool.

Doing so is worth the effort, as these metrics indicate the percentage of recipients who followed the email’s CTA to completion. 

These are particularly important metrics for measuring ROI and optimising your campaign goals.

8. Campaign performance (by campaign and by email)

Emails are almost never ad-hoc. They’re part of a larger customer journey, whether that’s a series of emails or a much more complex web of messaging across many channels. Often, a single email will be used in multiple journeys, at different stages or for different audiences.

No matter the case, it’s critical that email marketers don’t consider email performance in isolation: They must examine email performance by campaign, and evaluate the performance of specific emails in relation to the whole customer journey. 

Creating distinct email marketing KPIs for each can help; for example, click-through rate for a whole campaign versus click-through rate for individual emails across multiple campaigns. Doing this will help you understand why a campaign is working or not, and which emails to use in future campaigns.

9. Subscriber list growth and trends

The health of your subscriber lists is paramount. Are they growing? Are they stagnant? Declining? Tracking the status of your various lists and segments is a vital indicator of how your emails are performing over time, and if your email sign-up CTAs are effective.

It’s particularly important to view subscriber list health in context of specific campaign and email performance. Try looking at other KPIs mentioned previously (such as CTR, bounces, delivery rate) and list growth for the same period. Is there a correlation in low CTR and stagnant email list growth? 

Perhaps complaints jumped from a specific email to a list segment, and your list declined in response. These can all give you indications on what to improve in the future.

10. Most and least engaged subscribers

Likewise, it can be a great exercise to regularly analyse which subscribers in your lists are most and least engaged. High engagement may indicate a customer with high brand loyalty, who maybe should be targeted in an upcoming loyalty offer. 

Low engagement, on the other hand, may mean they need to be re-targeted; or perhaps, be removed from your lists altogether. After all, the size of your lists ultimately is not what’s important. It’s how many people on those lists are actually engaging with your content.

While email marketing continues to change, the core principles have remained the same: Give your customers something of value, and they’ll return the favour. 

Tracking your success in doing this, however, requires an agile mindset. While these email marketing KPIs can help get you started, you shouldn’t stop there. Always keep learning, testing, and evolving.