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Performance-boosting tips for email subject lines

by Kate Lindemann  |  October 30, 2020

8 min. read

Subject lines are your email’s first chance to make an impression, so it’s important to get them right. After all, customers have to open your email before they can experience what’s inside.

These simple strategies will give you the tools you need to pique your customers’ interest and keep them reading.

Rules of thumb for all email subject lines

Some strategies work no matter what type of email you’re sending. Use these rules of thumb for all your subject lines to give them the best chance at success.

Keep it short

Most email clients will cut long subject lines off, especially on mobile. Stay under 50 characters. Fewer is even better.

Start off right

Whenever possible, put the most important word or phrase at the beginning of the subject line. That way, customers see it first. Plus, you’ll know for sure your message won’t end up hidden behind an ellipsis on narrow screens.

Let’s look at an example. These two subject lines contain the same information:

This Week Only – Everything Is 20% Off

20% Off Everything This Week Only

But only the second gets the full message across when a narrow screen cuts it off:

Email subject lines cut off on narrow screen.

Be accurate

Make sure your subject lines reflect what’s actually in the email. Clickbaity subject lines may boost open rates initially, but customers will be disappointed if the content inside doesn’t live up to expectations.

Plan ahead

We’ve all been there. You’ve created the perfect email campaign, agonizing over the messaging and design. You’re ready to hit ‘send’ and… oh right, the subject line.

It can be tempting to just jot down two okay-ish options and let the A/B test sort out the rest. But email subject lines are too important to be left to the last minute.

As you design a campaign, set aside the time to write several solid options. Then, come back to them the next day with fresh eyes to see which you like best.

Even better: get a second opinion. Subject lines are all about first impressions, and you’ve been steeped in your email campaign for hours. Recruit a colleague (or two) to weigh in with an outside perspective.

Chat conversation about subject line options.

A/B test

Email subject lines are practically made for A/B testing. So take the two winners of your informal office poll and pit them against one another.

Not only will you improve open rates for individual campaigns, you’ll collect valuable data with every email. Over time, you’ll learn what types of subject lines customers find most persuasive.

Use the preview text

Even though the subject line will do the heavy lifting when your email appears in customers’ inboxes, it’s also got backup. The message preview is valuable – and often underutilized – real estate.

Far too many emails show up in inboxes with message previews like this:

Underutilized email message preview.

If yours are among them, it’s time to reclaim that space. Use it to provide additional context and any important information that didn’t make the cut in your subject line.

Some email providers give you the option of entering a preview text in a separate field. Others default to the beginning of your message. In either case, don’t let those characters go to waste.

Use your brand

The ‘From’ field also provides important context for the subject line. If customers recognize your brand and know what to expect, you can leave some things unsaid.

On its own, this email subject line is… confusing:

Unbranded email subject line.

But with the context of a well-known brand, the meaning becomes clear:

Brand gives new meaning to email subject line.

Stay true to your brand

As you experiment with different writing styles in email subject lines, don’t stray too far from your brand’s usual style.

If your voice is usually serious and professional, a cutesy subject line out of nowhere will undercut brand identity. Instead, show a consistent personality, so customers can develop a relationship with your brand over time.

More subject line strategies

While the tips above apply to every email subject line, other strategies are more mutually exclusive. Even if you could cram them all into one subject line, the result would be pretty ridiculous (and way too long):

Sandra, just one week to Halloween! Get your lawn decor now to be the spookiest house on the block in Kansas City 🎃

Instead, use one or two of these strategies at a time – whichever fits best with your brand, audience and the type of email you’re sending.

Be straightforward

More often than not, the most straightforward email subject line is also the best. After all, the main purpose of the subject line is to let customers know what the email’s about.

If you’re being thoughtful about sending emails customers want to receive, the most compelling subject line is one that tells them exactly what they’re getting.

Straightforward email subject lines.

Focus on value

Subject lines have to state the case for why someone should open your email. Think about the essence of what the email offers. The solution to a problem? A money-saving discount? An expert perspective? Whatever that value is, make sure it comes across loud and clear.

Email subject lines showing value.

Be playful

If whimsy and humor are part of your brand identity, unleash your creative side. A playful email subject line can be a good way to mix things up in customers’ inboxes.

It can be hard to be both informative and creative at the same time. If you need to, use the message preview to spell things out more clearly.

Playful email subject lines.

Use names

Using names might just be the most common piece of email-subject-line advice out there. And it’s true: data shows that using names increases opens.

Just don’t expect miracles. The impact in most industries is relatively small. Names in subject lines make a bigger difference in sectors like government and non-profits than in marketing and advertising.

It’s easy to guess why. Some people find seeing their names in marketing copy a bit creepy: Why is this big corporation trying to be my friend? But in fundraising, personal pleas feel a bit more natural.

Fundraising email subject lines using first names.

Be local

Of course, names aren’t the only way to personalize an email subject line. Location is another option that feels a bit less intrusive.

Cities in email subject lines.

If it’s urgent, let them know

People react to time-sensitive subject lines, especially those that use the word ‘urgent.’

However, the urgency card is hard to play with marketing emails. It’s not easy to make the case that buying shoes needs to happen right now. Instead, consider more subtle ways to dial up the time pressure:

Email subject lines conveying urgency.

Create a sense of scarcity

Time’s not the only thing that can run out. Scarcity also creates a sense of urgency and makes things feel more valuable. So tap into customers’ FOMO and let them know if they need to hurry.

Email subject lines conveying scarcity.

Use emojis (or don’t)

Emojis in email subject lines are a divisive subject. People seem to either love them or hate them.

In most cases, it’s up to you. If you want to use one or two to add some visual pop, go for it. They’ve become commonplace enough that it won’t scandalize anyone.

Just don’t force it. Emojis have to fit naturally into your subject lines. Never use one just for the sake of using an emoji.

Emojis in email subject lines.

Find an occasion

Marketing emails out of the blue can feel a little intrusive. Customers are more likely to engage with an email if you have a clear reason to send it.

Look for opportunities to frame your subject line as news. If you’re launching a new product or opening a new store, the subject line practically writes itself.

Much smaller ‘occasions’ hold marketing potential too. Take lunch, everyone’s favorite time of day. When you get an email from your favorite delivery app right around noon, it’s not a coincidence. You probably don’t even have to open the email. The subject line alone is enough to make your stomach rumble and send you straight to the app.

Food delivery email subject line about lunch.

Embrace the season

A classic way to stay fresh and relevant all year long is to mention seasons and holidays in subject lines. These events make it easy to tap into universal experiences, so you can write subject lines that match what’s going on in your customers’ lives.

Seasonal email subject lines.

Call to action

The same principles that persuade customers to click though in an email can also work in the subject line. Be direct, use active verbs and make the result of the action clear.

Email subject lines with calls to action.

Now you’re ready to write your own

With these best practices in the back of your mind, you’ve got the tools you need to write high-performing email subject lines.

As you hone your craft, get inspired by the marketing emails in your own inbox. Keep a folder of good email subject lines you encounter in the wild to reference when it’s time to write your own.

Add a little practice and experimentation, and you’ll be writing subject lines in your sleep.

Of course, the subject line is just the beginning of a customer’s journey with your email. For more ways to improve email performance, check out our other tips for boosting email click-through rate.