A guide to writing catchy email subject lines that convert

You put work into your emails. Your copy is carefully crafted. Your images are perfectly placed. Your calls-to-action (CTAs) are strategic and help your email marketing work for you.

But all of these aspects hinge on one crucial part—the subject line.

Think of your email subject line as the door to your content. Everything you offer is behind it. The key is convincing the reader to go through. Subject lines should reveal enough to get the reader interested but leave just enough mystery.

Even as a seasoned email marketer, you need to know the right steps for crafting an email subject line that drives the conversions you’re looking for.

Tips for writing catchy email subject lines

Before you can create email subject lines that convert, you should know exactly what we mean by “conversions.”

Email marketing conversion rate is the percentage of subscribers who complete a desired action. Easy, right? We should also note that email is a versatile marketing tool, so the desired action doesn’t always have to be the same.

Maybe you want people to view a page, respond to a survey, or sign up for a subscription. All of these can be achieved with the proper email subject line.

1. Use numbers to promote offers

The world runs on data, and marketing should too. At least, that’s the case when you’re promoting a special offer. 

To those who pride themselves on writing gobs of promotional verbiage: Know that lengthy word counts don’t sell. Numbers do. Customers want to know what they could save, what they could win, or what they could gain.

email subject line examples

Source: Business 2 Community

When you’re coming up with a subject line, your instincts might tell you to talk about the sale or reassure your reader how much they deserve the deal. While these are great bits of information, you should open with numbers to drive home the value instead.

Given that 80% of people scan emails, putting a dollar sign or percent sign beside a number is a great way to grab attention. You can expect conversions like this: Signups, purchases, and offer redeems. 

2. Use fear when time’s a factor

Though fear is often considered a negative feeling, it has advantages. The fear of being late causes us to set alarms and turn in early. The fear of failing an exam makes us study harder and remove distractions. Likewise, the fear of missing out (FOMO) can help convince your audience to open your email.

Knowing how many days are left, how many slots are left, or how many products are still in stock can really drive people to act when they otherwise would’ve passed.

“3 DAYS left on the blowout sale.”

“Only 5 webinar spots left.”

“Don’t miss this amazing opportunity.”

The last example doesn’t use a number, but it still creates FOMO. Is it possible that the email would wind up in spam? That depends on the reputation of the sender.

email example using FOMOSource: Really Good Emails

If they trust you and your content is usually good, you can create FOMO without numbers. Just remember that the body of your email needs to live up to the hype you create.

What conversion benefits might you reap here? Last-minute signups and sales. 

If your company is trying to bring up its numbers, you should be trying this tactic.

3. Stimulate curiosity 

If you’re looking to get people interested in informative content, you have to catch their interest quickly. Think about other forms of promotion. They sell you a snippet or taste. The same approach works with email—the subject line is the place to pique interest.

Let’s say you’re putting out blogs, news articles, newsletters, white papers, or case studies. This content is designed to inform, entertain, and facilitate engagement based on its ability to keep the reader interested.

There are a few strategies you can use here. Ask an interesting question that makes people curious. 

“How will artificial intelligence impact your healthcare?”

You could also use the reader’s name in a way that makes the content seem personal.

“Josh, here’s what your buying habits say about you.”

email strategies to stimulate curiositySource: Really Good Emails

These touches are helpful for getting people to engage with an email. Remember, a lot of email marketing is about building your brand—keeping a conversation going. That means informing and educating without trying to sell something (at least materially) every time.

The type of conversions you’ll get here are click-throughs and sign-ups for things like blogs and newsletters.

4. Be specific and personal with gratitude

There’s nothing like being noticed for the good things you do. As an email marketer, you may wish your content was noticed more. Your readers may sometimes wish their faithfulness to your brand (and your emails) could be recognized, too.

“Thank you” emails should always be a tool marketers use when appropriate. You can thank your subscribers for specific actions or milestones. If they’ve been on your mailing list for a year, you can send an email to thank them for sticking around.

The formula here is simple. Make it personal. Talk about what they’ve done and use their name if possible. It makes the email sound more sincere and lets the reader know why they’re being recognized.

email example of personalizationSource: Really Good Emails 

Sometimes all you’re aiming for with these emails is an open. In other cases, you may want to get your reader to claim a reward or even renew their subscription.

5. No matter the content, keep it simple

In marketing, simplicity wins—especially when you’re working on a catchy email subject line. It’s good for your reader too, because it gets straight to the point. 

You may have a ton you want to convey. You may have put a lot of work into your emails. The same can be said of your brand and the products behind it. But you don’t want to begin with too much complexity. 

Your reader could get overwhelmed by your subject line. And once that happens, they likely aren’t going to see what’s inside your email.

The good thing: Your subject line is a short amount of space. This can actually be valuable—because, as a result, you have to be concise. Go for no more than 60 characters with proper keywords.

When you think simple, think about eliminating filler words. Skip the hello. Say what you have to in as few words as possible.

Poor: “Hey, check out these awesome deals just for you!”

Okay: “Awesome deals just for you.”

Good: “50% off deals, chosen just for you.”

Per our previous tip, use a number to gain the reader’s attention. 

Poor: “What makes a small business succeed? Here’s the secret.”

Okay: “Read on to make your small business succeed.”

Good: “A secret for small business success.”

airbnb email example of simplicitySource: Really Good Emails

This is an example of how to arouse curiosity. The second version is better because it’s more concise, but you can still trim it down. Remove “read on”. Your reader already knows you want them to read on. Don’t tell them to, make them want to. 

Wrap up

Email subject lines are arguably the most important part of email marketing. The success of your emails depends on communicating the perfect verbiage. What we’re saying is that writing catchy email subject lines is an art—and mastering it isn’t easy. 

Your conversion goals may be different each time you send an email, so your practices will change. But some habits are effective no matter what you’re aiming for. Remember:

  • Use numbers for deals and names for personalization 

  • Arouse curiosity through questions and bite-sized information

  • Stay simple, concise, and free of filler words

Ready to target different types of conversions? Learn how to boost your open rates with these subject line ideas. 

About the Author

Emma Email

Emma is an email marketing platform that gives you all the tools you need to send campaigns that really connect with your subscribers. With our​​ powerful automation and personalization features, you can create and send email campaigns that reach the right customer at just the right time. It's email marketing that works for you.

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