7 principles for high performing email

A lot of companies use email as a fixed part of their marketing mix. They understand the power of this channel to start a conversation with your customer or lead by offering them content with added value. Whether you have sent thousands of emails or you’re up to your first email campaign, the principles remain the same. Unfortunately, we see too often that these principles are ignored, leading to great frustration at the receiving end.

Email is a powerful instrument if used in a good way. Therefore, follow these principles in your email marketing campaigns and improve your results.


A lot of ink has flowed over this in recent years. Since May 25, 2018, everyone knows that you do not send emails to people who have not permitted you to do so. At least, everyone should know that. Tell me, how do you feel about a commercial email in your inbox from a sender you don’t know and a subject you’ve never heard of?

Always ask yourself whether you have verifiable permission from all your contacts. It is best practice to have your contacts actively subscribe to your mailing list. This can be done via your website, during a purchase, at an event, … the possibilities are endless.

If you work with online registrations you should consider using a double opt-in. You send your new contacts an email with a link to confirm their registration. This way you can be sure that the email address belongs to the person who registered. You also create extra interaction with your brand. The downside is that your list could grow a bit slower, but your contacts will become much more qualitative.


The main purpose of any email should be the added value for the recipient. Only after that, you should think about your own business goals. Therefore, always try to make your message as relevant as possible to the recipient. This can be done in different ways:

  • Respond to the expectations you created earlier when the recipient subscribed to your mailing list. These expectations are a crucial part of your email marketing strategy.
  • Divide your mailing list into segments based on common characteristics of your contacts. These can be demographic characteristics such as age, gender, place of residence, … But it is even better to include behavior in your segmentation. For example, you can group all contacts who have read your blog on a specific theme.
  • When drawing up your message, always start from the characteristics of the segment. Don’t forget you are writing the message for them. So don’t always start from your own company or product.


Personalization has many forms and you can take it as far as you wish. In any case, it is best to personalize your introduction by using the name of your contact.

Do you have other information about your contact available such as company, location, etc.? Then you can use this information to make your emails more personal. You can use these elements in your subject or preview text too. Although the success of the name in the subject decreases, there are many other possibilities.

A thorough example of personalization comes from the cinema chain Kinepolis. Every email they send is unique. They do so based on a large number of variables including gender, age, previously booked films, preferences of your online profile, etc.

Of course, it doesn’t have to go that far for a smaller company. But the more personal your content is the more relevant to your contacts, and the better your email will perform. That way, you also build a valuable relationship with your contacts.

Subject line and preview

The subject line is your first impression, meaning it’s crucial. Mailboxes are so full these days that people decide in a split second whether to open an email or not. So your subject has to be attractive, relevant, and just long enough to invite you to continue reading.

‘Just long enough’, what does that mean? In recent years, the share of mobile devices for email has been growing strongly. Since you want your subject to be fully visible at all times, you have to take those smaller screens into account. That’s why it’s best to limit the length of the subject to 40 to 50 characters.

However, don’t be tempted to forget the essence of the email in that relatively short sentence. Your subject must closely match the content of the email to meet the expectations of the recipient.

Your choice of words will have a big impact on the open rate of your email. Words like ‘Exclusive, Now, Only Today,  Last Days, …’ indicate urgency. Other words like “Promotion, Savings, 2+1, 50%” indicate that there’s something to be gained. However, be careful with percentages and words like ‘Free’ because spam filters are sensitive to this. Also, don’t use the above words too much as the effect could diminish after a while.


A well-designed email will guide the reader through the content to ultimately take the desired action, your goal. To achieve that, you start from your goal again and set up the entire email from there. Include only what is relevant and necessary to support the goal. Leave everything else behind, even if you have so much to tell.

Give the reader visual hints by using titles and accents. Limit the body to what is strictly necessary. This makes the email easy to quickly scan. Each element supports the call-to-action in your email.

Create an experience with your email that is consistent with other channels of your brand. The reader should immediately recognize your brand by the use of color, logo, font, language, etc. A wonderful example of this? Bol.com. Everywhere (website, social, email, …) where you encounter the brand, it seems as if you’re talking to the same person. This is further supported by a recognizable use of color and recurring elements.

Last but not least, you should not forget the different email clients. Emails can be read in countless ways: Apple Mail, Outlook, iOS, Android, Gmail browser, … So make sure your email looks flawless everywhere. You can test this on different email platforms via previews. And in case something should go wrong, always provide a link to view the email in a browser.


Is your database large enough? Then you can improve the performance of your emails by testing them. But beware, don’t jump to conclusions. Testing is a strategy and you have to do it constantly to recognize patterns.

Before you start testing you need to set a clear goal; why am I doing this test and what do I expect to get out of it? Do you want to improve your open rates? Then test different subjects and preview texts. Is your CTR (click-through rate) disappointing? Experiment with different body texts or call-to-actions.

In an A/B test you will compare two (or more) versions of your email. Always work with specific small differences. This way you can determine which element caused a possible difference in performance. Always keep in mind that you need a minimum of contacts to do a successful test. You can calculate that number with this calculator.

Finally, you should avoid stopping your test too early. Look at previous emails and when the opens and clicks decrease on average. Is it always after 2 hours or after 2 days? This way you know how long you need to run a test to draw conclusions.


To measure is to know. And when sending emails you can measure a lot. Use these metrics to check how your emails and strategy are doing. You should look at the KPIs on different levels.

Per email, you will see how many emails have been delivered and how many have been opened. You also measure clicks and conversions. Additionally, keep track of every conversation started from the email. This way you get a picture of the individual performance of your email. Compare these with other emails of your brand to spot trends. Comparing with benchmarks can be difficult because there are so many variables.

Another level to look at it is per channel. Compare the performance of your email marketing strategy with other channels you use for your brand. What is the impact of your email campaigns on your business? Does it improve your customer relationships? Do you have an impact on customer lifetime value? What about the ‘health’ of my database?

Eventually, you should also calculate the return on investment (ROI) of your email campaigns and compare it with other channels. What extra return on investment has come from email? Take into account all costs; email platform, time invested, purchase images, design agency, etc. You can then compare this ROI with other channels again.

The ultimate goal of all the analysis? Adjusting your campaigns to improve performance! This way you will discover what is really relevant for your target group.


Written by Gilles Van Lysebeth, BrainTower Consultant.

Do you need help developing your email marketing strategy? Want to improve your email marketing performance?