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  • Writer's pictureJennifer Heppell

The Ultimate Guide to Email Subject Lines

“The content of your message is really what determines which words you use, but with so few words in a subject line, each one matters quite a lot.”

— Neel Shivdasani, data scientist at MailChimp

Email subject lines are crucial in email marketing as they are the first thing subscribers see in their inbox and can determine whether your email gets opened. Without compelling subject lines, your email marketing efforts might not yield the desired results. Emails remain a prevalent communication tool between businesses and clients, with a staggering 347.3 billion emails sent every day worldwide in 2023. That’s an astronomical number, equivalent to a digital symphony of communication spanning the globe! 

However, many businesses underestimate the influence of a well-crafted email subject line on sales and growth. If clients find your emails annoying, they may stop opening them, leading to missed promotions, unseen product updates, and lost repeat business. But don’t fret, with the right strategies to tailor your email subject lines, you can enhance open rates, engagement, and see improved results from your email marketing efforts.

A laptop on the table.

                                                                                               Key Elements of Effective Email Subject Lines


The subject line of your email should be straightforward and succinct, accurately reflecting the email’s content. Avoid using unclear or misleading language that could puzzle the reader. A clear and concise subject line helps the recipient understand the email’s purpose without needing to decipher it. 

Ambiguous or confusing subject lines may decrease the email’s open rate as recipients might not recognize its relevance or could mistake it for spam.


Maintaining an air of mystery can be effective, especially if it sparks curiosity. Such subject lines often lead to higher open rates because recipients want to uncover what lies inside. It’s essential to strike a balance: intriguing enough to encourage opens but still aligned with your brand. Overly cryptic subject lines might be mistaken for spam.


Ensure that your email subject line is pertinent to your readers and matches their interests or requirements. Tailoring it can greatly boost its relevance and increase the chances of it being opened.

When a person signs up for an email, they aim to stay updated with recent events or gain knowledge about a specific subject. Therefore, the subject line should reflect current trending topics or interests, which aids in building the brand’s identity and credibility in its respective field.


Use language that makes people feel like they need to act fast because they might miss out on something important. Urgency triggers a feeling of FOMO, which makes recipients want to open and respond to the email as soon as possible. It taps into their fear of missing out on a valuable opportunity, prompting them to take action promptly.

7 Tips on Crafting Better Email Subject Lines

By implementing these strategies, you can create subject lines that resonate with your audience and encourage them to engage with your emails.

  1. Keep it Short

  2. Personalise Where Possible

  3. Use Action Oriented Verbs

  4. Ask Question

  5. Use Numbers

  6. Avoid Spam Words

  7. Test your Subject Lines

A woman writing and typing on her laptop.

1. Keep It Short 

For effective email communication, it’s crucial to use brief and clear language in your subject lines. This strategy allows recipients to quickly understand the email’s purpose or required action, thereby promoting prompt responses. In fact, 64% of recipients decide whether to open or delete emails based on subject lines. It’s also important to remember that most email providers truncate subject lines at around 50-60 characters. 

Therefore, keeping them short ensures full visibility. For instance, a subject line like “Flash Sale: 50% Off All Items!” is a good example of a concise and clear subject line that can effectively grab the recipient’s attention.

2. Personalise Where Possible

Everyone likes to see their name, it makes them feel recognized and valued. Using personalised fields like the recipient’s name in your subject line can significantly boost the email open rates. It gives the impression that the email is specifically meant for them, helping your email to stand out in a crowded inbox.

For instance, using a subject line like “John, Your Customised Weekly News Digest” can make the email more appealing to the recipient. Interestingly, this tactic is currently utilised by 34% of marketers in the US and the UK, highlighting its effectiveness and growing popularity in email marketing strategies.

3. Use Action-Oriented Verbs

When crafting an email’s subject line, include a call to action. This clarifies the purpose of your email and indicates what you want the recipient to do.

Remember, the goal of marketing emails is to prompt action. So, incorporate a call to action in your subject line as well.

For example, beginning your subject line with an action verb can motivate readers to click. A subject line like “Discover the Secrets of Successful Entrepreneurs” is a good example of this approach.

4. Ask a Question

Using questions in email subject lines is a key trend in email marketing. It draws readers in and boosts open rates, with statistics showing that email subject lines with questions have a 50% higher open rate. Examples include “Are you making these SEO mistakes?” or “What Can You Afford?”. Companies like Zillow and DocuSign have effectively used this strategy, linking to relevant content and using customer testimonials to move potential customers closer to purchase. 

This approach clearly demonstrates the power of well-crafted subject lines in driving email engagement.

5. Use Numbers

The use of numbers in subject lines and titles is a powerful tool in capturing a reader’s attention and making information more digestible. For instance, a subject line like “5 Tips to Increase Your Productivity” immediately stands out and provides a clear expectation of the email’s content. This strategy is also why listicles are popular. 

According to Campaign Monitor, incorporating numbers, especially at the start of titles and headlines, can more than double the traffic to blog posts. Numbers not only grab attention but also enhance credibility, reinforce promises, and provide specific information. For example, “11 Ways to Convert Subscribers into Customers” is a more effective subject line than a vague one like “About Your Email Subscribers and Customers”. It offers a specific promise and sets clear expectations for the reader.

6. Avoid spam words

Subject lines with an overly promotional tone are more likely to be flagged as spam. This includes the use of excessive punctuation, such as all caps and multiple exclamation points, and overtly sales-oriented language like “Buy now” or “Free”. Such tactics can lead your marketing emails directly to the spam folder. Instead, it’s advisable to focus on sharing your expertise and providing valuable information to your audience. 

Avoid using clickbait phrases or making unrealistic promises, as savvy readers will quickly mark such emails as spam. Minimise the use of exclamation points or capital letters, as recipients may not share your level of excitement about the email. By adopting these strategies, you can craft effective subject lines that resonate with your audience and avoid the spam folder.

7. Test Your Subject Lines

The final, yet crucial step in optimising your email subject lines is testing. Even if you meticulously apply all the tips mentioned, it’s impossible to predict their effectiveness without testing them with your audience. A/B testing is a powerful tool that allows you to divide your audience and test two distinct subject lines, providing valuable insights into what resonates with your audience and what doesn’t. This knowledge enables you to craft more effective subject lines in the future.

But the beauty of A/B testing is that it’s not limited to subject lines. You can also test other elements like preheaders, email body content, and sender addresses. The key is to test one element at a time to get a clear understanding of which tactics enhance performance. By incorporating A/B testing into your email marketing strategy, you can continually refine your approach and maximise the impact of your emails.

Final Thought

The ultimate aim of an email subject line is to entice the recipient to open the email. It should provide just enough information to pique the reader’s interest, but not so much that they feel they’ve gleaned everything without needing to open the email.

Remember, if your emails aren’t being opened, they’re not being seen. By applying the tips shared, you can craft creative and engaging subject lines that do justice to the great content you have to share.

So, don’t hesitate to reach out and let’s start making strides in your email marketing campaigns by mastering the art of crafting compelling email subject lines. Happy writing!

A woman typing on her laptop while having a paper and pen beside her.


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