The most important metrics in email marketing: How to measure success

Delivery rate: Are your emails getting through?

The delivery rate indicates the percentage of emails sent that successfully reach your recipients. This describes the first hurdle—that your sent emails actually end up in your customers' inboxes. According to Mailjet, this email marketing metric should be in the range of 95 to 100%.

Open rate: Are your emails being opened?

Once the email has been successfully delivered, the next hurdle is getting it opened. The open rate describes the proportion of delivered emails that have been opened at least once. A distinction can be made between single opens (unique open rate) and multiple opens (total open rate). While the unique open rate counts only one opening per recipient, the total open rate includes all openings of the email (including multiple openings by individual recipients).

Since this metric allows you to determine whether your recipients open your email or whether it ends up unread in the trash, you gain valuable information about whether your content is interesting and whether the subject line is appealing.

According to OMT, the open rate should be between 20 and 25%.² However, this value can depend on various factors, such as the industry, the subject line, the sender's address, the time of sending, or the frequency of sending.

Example of the evaluation of the open rate compared to average values and those of similar users (source: Mailchimp screenshot)

To optimize your open rate, you can start with these points. For example, choose an appealing subject line that grabs attention. Many recipients decide whether to open an email based on the subject line. Address your recipients directly by name in the subject line or ask questions that pique their curiosity. Wordplay or emojis can also attract attention. Be sure to avoid spam-heavy words or characters, such as "free," "limited offer," or "you've won." You can find many more email spam words in this blog article from HubSpot.

The design of the pre-header (preview text of the email in the form of a short description) can also influence the open rate. You should also design this in an appealing way and motivate your recipients to read on and open the email with an inviting call to action.

Subject line and pre-header of a newsletter as an example (source: Mailchimp screenshot)

By choosing a trustworthy sender address and not using a noreply address, you can also increase your open rate.

Furthermore, the time of dispatch can play a decisive role. Here, you can follow best practices or simply test for yourself which dispatch time has the best effect on your recipients. Various email dispatch tools can also calculate the dispatch time automatically.

You can find out more about optimizing open rates in this guest article: Improving newsletter open rates through subject line testing and send time optimization.

Click-through rate: Are your recipients interacting with the email content?

The click-through rate describes the number of recipients who clicked on one or more links in your email after opening it. This metric helps you determine the performance of individual emails and provides insights into how many recipients interacted with your content. This, in turn, shows whether your content is interesting to your readers and whether your customer approach is convincing. According to Mailjet, a click-through rate between 3% and 7% is considered normal.³

Here, either all clicks or each recipient can be counted only once. In the second case, this is referred to as the unique click rate.

Example of click-through rate evaluation compared to average values and those of similar users (source: Mailchimp screenshot)

To increase the click-through rate, you can, for example, send personalized emails that contain relevant content based on the interests of the respective user.

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You can also address your readers personally by name. The use of storytelling can also lead to higher click-through rates by generating emotions and building trust. The presentation of links and CTAs is also crucial in getting your recipients to interact with the content. Descriptive CTAs with clear calls to action and color-coded links or buttons can also increase the click-through rate. Make it clear to your recipients where they should click and what they can expect behind the link. In addition, the mobile view is also very important and should not be neglected.

Various email marketing tools allow you to view key figures directly in the form of reports and provide detailed analyses of your sent emails. If you would like to know more about how the individual key figures are calculated, you can find the formulas for calculating some key figures as well as calculation examples in an article by Christoph Hemmann on omt.de.

Conversion rate: Has the desired target action been completed?

The conversion rate email marketing metric goes one step further. It refers to recipients who clicked on a link and then performed a specific (desired) target action. These actions can vary greatly, such as filling out a form, registering for an event, subscribing to a newsletter, downloading informational material, or purchasing a product. To measure conversions, tracking URLs for email links, such as Google Analytics' UTM parameters, are helpful. This allows you to track which email generated how many conversions.

Since the target action or the recipient's action takes place on the website or in the online shop, it is important to consider the influencing factors there. For example, the page layout, the registration or download process, or usability can be decisive for a conversion.

Additional key figures for successful email marketing

In addition to the metrics presented here, there are many other email marketing metrics that are worth keeping an eye on. We would like to briefly outline some of them below.

• Bounce rate: The bounce rate represents the percentage of emails sent that were not successfully delivered and is therefore the counterpart to the delivery rate. You can distinguish between soft and hard bounces here. Soft bounces are temporary problems with a valid email address, such as a full mailbox or a temporarily unavailable server. Hard bounces, on the other hand, are emails that cannot be delivered permanently, such as invalid, deactivated, or non-existent email addresses.
• Unsubscribe rate: This metric refers to the percentage of recipients who click on the unsubscribe link in the opened email and thus decide that they no longer want to receive emails from you. Unsubscribes are quite normal and can have various reasons. It is possible that the recipient's inbox is full, their needs or interests have changed, the frequency is too high, the design is unattractive, or the recipient does not have enough time to deal with your emails. It is important to note that, for legal reasons, your email must always include an unsubscribe option. To find out why someone unsubscribed, you can provide a questionnaire that unsubscribers can fill out on a voluntary basis. You can use the insights gained from this to take appropriate optimization measures.
• List growth rate: In contrast to this is the list growth rate—the rate at which your email distribution list is growing. To increase your reach and expand your target audience, you should try to boost your list growth.
• Spam rate: You should also keep an eye on your spam rate. This indicates the number of recipients who have marked your emails as spam or the number of emails that have been classified as spam. A high spam rate can lead to emails from the same sender being classified as spam and sorted out in the future. It is therefore an important metric, and you should definitely avoid future emails ending up in the spam folder. Instead, make sure your emails pass spam filters successfully by avoiding spam-heavy words and characters, for example.
• Forwarding rate: The forwarding rate plays an important role when it comes to generating new contacts. It represents the percentage of recipients who clicked on a social media share button or forwarded your email.

Note: The metrics listed above are only a selection of important KPIs. Of course, there are other metrics that can provide you with information about the success of your email marketing.