How to write the best email subject lines: Your definitive guide

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The average open rate for marketing email across industries is only 35.6%. That means over half of branded emails are left unopened.

The problem? Poor subject lines. Without crafting an email subject line that inspires the recipient to click through and check out what you have to offer—all of your copywriting efforts will be wasted.

Crafting the best email subject lines for your business is somewhat of a dark art. But the good news is, we’re going to share some actionable tips to boost your email open rates right here in this guide.

Understanding your audience and goals

Writing an email subject line that speaks directly to your audience will increase your open rates in a big way. But who is your audience, exactly? That’s for you to decide.

Know your email subject line target

By knowing who you’re writing your email content for, you’ll be able to craft a subject line that addresses a special pain point while offering a personal touch that will spark positive engagement (a.k.a. get your recipient to open their email.

So, before you start conjuring up subject line ideas, take the time to understand your target audience as well as what they need and what interests them.

You can do this by creating buyer personas or profiles based on your ‘model customers’ and splitting them into ‘segments’ based on their demographics, location, interests or main pain points. Do this and you’ll lay down solid foundations for your email subject lines.

FYI: By segmenting your audience into categories and writing your subject lines for specific groups of consumers, you’ll give your email open rates a significant boost.

Define your email content’s purpose

Once you’ve selected your target audience or consumers, you should define the purpose of your email.

By understanding the key goal of your email marketing content, you’ll give your subject line the definitive direction it needs to offer personal value. And when you do that—you’ll get consistent results.

To give your email content—and subject lines—genuine purpose, decide whether your content is:

• Transactional: Is your email content functional or transactional? For example, an order confirmation, an abandoned cart email, a shipping notification or a welcome email.
• Promotional: Is the main purpose of your email to promote a new service, product, sale or event? This will usually require a sense of excitement, exclusivity or urgency.
• Newsletter-based: Is your email content a part of your ongoing customer engagement efforts or a wider marketing campaign? If so, your content and subject line will benefit from a touch of brand storytelling.

The anatomy of an effective email subject line

Now that we’ve laid the foundations, let’s get down to business by looking at the key elements of a killer email subject line—starting with length.

Email subject line length

To grab attention and ensure your email subject line is legible, length matters. While there’s no one-size-fits all solution, when it comes to email subject lines, you should make sure it’s no longer than 50 characters.

Keeping within the 50 character limit will avoid your messaging being cropped. It’s a character limit that works well with any device—it’ll also keep your messaging powerful and punchy.

69% of consumers will delete an email straight off the bat if they feel the subject line is too spammy. So keep yours short and sweet (around five to nine words is usually the sweet spot) and you’ll be onto a winner.

Word choice and tone of voice (TOV)

When you’re attempting to write the best email subject line for your business, every word counts.

To grab attention and inspire engagement, using strong verbs and marketing action words is key. You have five to nine words to make an impact—so you have to get to the point—and prompt action.

When you’ve drafted a potential email subject line, trim away anything that’s not absolutely essential to your messaging. Be clear, be concise, showcase your personality, and give your recipient a reason to click through.

Here’s a quick example:

Original: Learn How To Create Actionable Email Subject Lines For Your Brand Here

Improved: Get More Opens With These Email Subject Line Tips

The revised subject line is shorter, punchier, and creates a sense of intrigue or curiosity. It also makes a bold promise. Just remember that if you make a promise, you must deliver on it or you risk damaging your brand’s reputation.

Create a sense of curiosity or urgency

Following on from my last point: to prompt someone to engage with your content, your email subject line needs to serve up a slice of intrigue or urgency.

By asking a question, creating a sense of curiosity or teasing something that may be time-sensitive or exclusive, you’re far more likely to prompt people to interact with your email content. Let’s look at some examples.

Urgency

• [Recipient Name], Grab Your Discount Code Before It’s Too Late
• Our Biggest Ever Sale Has Arrived. Don’t Miss Out

Curiosity

• Do You Know About The Power Of Tech Investments?
• Can We Tell You A Stock Investment Secret?

Exclusivity

• Unlock Your Epic VIP Perks
• [Recipient Name], Grab Your Insider Email Marketing Guide

Common email marketing mistakes to avoid

Now you know the key elements of an effective email subject line, let’s look at what not to do—starting with the pressing matter of not looking spammy.

Don’t appear spammy with your email subject lines

Yes, one of the biggest mistakes you can make is writing spammy subject lines. Speaking of spamminess, there are certain words you just need to avoid altogether, even if they are the actual subject of your email.

FYI: The number of spammy keywords is growing. Prospect.io came up with a list of 455 spammy email keywords while Automational counted 474. Steer clear of these turns of phrase and you’ll avoid ending up in the spam box or having your email deleted from existence.

Ignoring personalization

Emails with personalized subject lines are at least 26% more likely to be opened. In today’s hyper-connected digital world, you have to connect with people on a personal level. 

One-size-fits-all sales jargon no longer cuts the marketing mustard.

By adding personal touches like your recipient’s and looking at relevant data to understand what makes your target reader tick, you’ll hit a personal nerve that’s likely to prompt action.

Remember, like any marketing medium, email is all about offering personal value—and it all starts with your subject line. Be as personal as possible and you’ll enjoy the results you deserve. Don’t ignore this fact.

Forgetting A/B testing

So many small business owners overlook the value of A/B testing—but it’s essential to understanding what works and what doesn’t.

Overlook A/B testing and you’ll be missing out on essential insights that will help you squeeze the most promotional juice out of every one (or at least most) of your email subject lines.

Working with the right A/B testing software, you can roll out two different subject lines for the same piece of email content and analyze which yields the best results. 

Doing this will not only lead you to the best email subject line, but it will also give you a practical gauge on the words, tone, approach, and style that resonates with your audience. Overlook the power of A/B testing and it’s unlikely that you’ll ever reach your full email marketing potential.

Advanced email optimization techniques

Use these insider optimization techniques to improve your email marketing subject lines and push yourself ahead of the pack.

Use emojis (but sparingly)

Using emojis in your email subject lines can draw visual attention to your messaging and punctuate a word or statement in a positive way. But don’t overdo it (remember what we said about being spammy).

Using a flurry of emojis will take up valuable messaging space within your subject lines and cheapen your brand image. But, one or two well-placed emojis will grab attention and inspire action. Here’s an example.

Overdoing it: Make Serious 💲Savings With Our Epic Sale 🤑🤑🤑💸

Sweet spot: [Name], Make Serious Savings With Our Epic Sale 💲

The first version of our email subject line is too busy, visually noisy, and looks cheap. On the flip side, the second includes one well-placed emoji that’s relevant and grabs just the right amount of visual attention.

Leverage pre-header text

Pre-header text allows you to expand on your email subject line just like a regular sub-heading. Your pre-header text is usually displayed just below your subject line and can offer extra context, excitement or inspiration.

Here’s an example for your reference:

Subject line: [Name], Make Serious Savings With Our Epic Sale 💲

Pre-header: Explore our exclusive deals & VIP-only offers and save big on your favorite products

And here are some quick tips on writing power pre-header copy:

• Keep it to a character limit of 130
• Reinforce the messaging in your subject line and offer a little more detail
• Build extra excitement, exclusivity or urgency where you can
• Avoid unnecessary jargon and highlight the benefits of opening the email

Keep up with emerging trends

Like any branch of marketing, email moves and evolves at warp speed. To keep on top of your game and continue writing killer email subject lines that get results, you need to keep up with the latest trends.

By reading industry publications, listening to relevant podcasts, signing up to email marketing newsletters, and following relevant influencers, you’ll keep your finger well and truly on the pulse—ensuring your email subject line writing efforts stay sharp in the process.

Final thoughts

Writing the best email subject lines for your business (the kind that earns consistent results) is no easy feat—but it’s more than possible.

By keeping it consistent, showcasing your brand’s personality, and following the actionable tips we’ve covered in this guide, you’ll start to see a big improvement in your email open rates. You’ve got this.

Do you have any thoughts, opinions or advice on the subject? Share them here by leaving a comment. Let’s get the conversation started.