10 tips for subject lines that will boost your email open rates

It’s commonly known that you shouldn’t judge a book by its cover. But don’t we all do that instinctively? The same happens in email marketing. If you want your subscriber to open your emails, you need to make sure they stand out in the inbox. And it all starts with the subject line. It’s the first impression your email makes, and the key to your subscriber’s engagement. It needs to be clear, relevant and should catch the interest of the reader.

Below, you’ll find 10 surefire tips to write subject lines that boost your email’s open rates.

1. Keep it short

Your readers should see what your email is about at a glance. If your subject line is too long, your subscribers will not be motivated to open your email and read it completely. Our golden tip: limit your subject line to 50 characters. With the mobile revolution, a growing number of people read their email on a smartphone, which automatically cuts off the length of your subject line. So it’s better to ditch unnecessary words such as update or newsletter and focus on your core message.

2. Make it active

By using action-triggering words, you encourage your readers to do what you want them to do. Active sentences help to create a visual representation in your reader’s mind, which can create a certain excitement that triggers your reader to open the email and continue reading. See your subject line as a type of CTA, with the ultimate goal of generating a click.

3. Include emojis and symbols

Adding a distinct visual element, like a symbol or an emoji, can reinforce the text of your subject line and trigger your reader’s curiosity. However, this only works if the symbol complements your message. Be sure not to overdo it. The use of emojis also depends on your company’s image and the tone of voice of your email. In some industries, implementing an emoji is a definite no-go. Find out if this approach works for your target group, by running an A/B test.

4. Create a sense of importance or urgency

“Download now”. “30% discount for early birds”. “Only 5 seats left for the cheapest flight to New York.” These subject lines provoke a sense of urgency and scarcity, which can trigger your reader to take action. By emphasising the exclusivity, you give your readers a gentle push towards action. This makes it easier to overcome their hesitation and have them proceed immediately to the email. This type of subject line is ideal when emailing about a promotional offer.

5. Use numbers

Tip 5 follows tip 4 perfectly. By adding numbers to your subject line, you send out a straightforward message about your offer. The numbers set the right expectations to highlight your offer. A number usually refers to a specific discount, but you can also let your subscriber know how long the discount is still valid. F.e. "Only 2 days left to take advantage of our free shipping."

6. Pose a question

Questions are strong curiosity triggers. That is, if they’re relevant. If you can pinpoint the position of your subscribers in the customer journey, you can send them an email with a corresponding question in the subject line. If you answer the question further on in the email, you can kill two birds with one stone: subscribers will be inclined to open the email and if the answer meets their needs, they will move further into the funnel.

7. Be creative

Think outside the box. Try something beyond your comfort zone and surprise your subscribers. A little joke, a smart pun, or something inventive that your readers might not expect. Anything that could draw attention in their inbox. To be used wisely, and only when you feel your target group is open for it.

8. Make it personal

Email personalisation increases your open rates. As you can read in our blog How you can personalise your email marketing and boost results, personalisation goes way beyond inserting a name in your subject line or body copy. But it definitely is a start. Addressing someone directly is an effective way to get someone’s attention, both in real life, and in the inbox.

9. Make your reader feel special

Everybody wants to be part of the ‘inner circle’. And your subject line is an ideal opportunity to address that need. By giving your subscribers a sense of belonging, you can establish a loyal relationship, which will make your subscribers open your emails. Conversational words like you and your work like a charm: “We have a gift, especially for you.” “You’re invited to our exclusive event”. It’s a psychological thing: exclusivity works.

10. CAPS, question and exclamation mark

Spam filters look for certain criteria in emails that trigger your email to be categorised as spam. Some of these criteria apply to the subject line. IF YOUR SUBJECT LINE IS WRITTEN COMPLETELY IN CAPS, it will often be seen as spam. Plus, nobody likes being yelled at. Another key criterium is punctuation. An exclamation mark can certainly give some extra power to your subject line, provided you limit it to 1 exclamation point. Use more exclamation marks and your email could end up in the recipient’s spam folder. And did you know that the combination of a question mark and an exclamation mark in the subject line can get your email flagged as spam? 


These 10 tips above help your emails get more response. But what works for one company, doesn’t necessarily do the trick for another. It’s best to A/B test in order to find out which subject lines get the highest open rates for your business. And the higher your open rate, the more clicks you can generate and the more profitable your ROI will be.

Do the Email Marketing ROI-scan

Posted on
May 22, 2019