What Is The Curiosity Gap? (How to Use It For Better Email Subjects)

Apr 11, 2022 | Email Marketing, How To

The curiosity gap is a theory that has been around for years.

But now, it’s being used as a content marketing strategy. People want to know what’s coming next. So, when something interesting comes up, they are naturally curious.

You can leverage this curiosity in your email subject lines to get more of your audience to read your emails.

What Is the Curiosity Gap?

The curiosity gap is the void between what you know and what you don’t know.

Humans have a healthy sense of curiosity. We have a built-in need to know. When we get curious, we feel it as a mental “itch” that must be scratched.

You can use this internal motivation when writing your headlines to increase your click rate and get more eyes on your content.

How The Curiosity Gap Technique Works In Email Subject Lines

The job of the email subject line is one thing: to get the reader to click, open, and read the email.

To create the itch and the motivation to scratch it, you need to give your audience three things in your headline: What, who, and a promise — without giving away the answer. So, enough information to get them to click through, but not so much information that they don’t need to click through.


For the what, be clear and specific. This is not the time to get cute and clever. In headlines, true creativity is the intersection of clarity and brevity. So make sure your headline tells the reader what this content is about. (Seems obvious, but you’d be surprised how often folks resort to cute and clever.)


For the who, call their name. After your reader knows they’re interested in your ‘what’, the next question they’ll ask is who? Who is this for? You want to be specific enough that your reader instantly knows yes, this content is for me, or no, this is not for me.


For the promise, make them drool. People are busy and skeptical. Let them know why your article or blog post is worth their time. Make a promise they can’t resist. Tell them why they should click.

And when they do click through, you’d better deliver.

Curiosity Gap vs Clickbait: What’s the difference?

Curiosity gap email subject lines and blog post headlines are not automatically clickbait.

What makes a headline “clickbait” isn’t that it uses numbers: 7 Ways, 13 Reasons, 3 Steps, etc. These headlines are very effective. And it’s not that it uses extreme adjectives: Irresistible, Amazing, Mistaken, etc. These words evoke an emotional response, which is great. What makes it clickbait is the reader clicking through to the actual content and feeling tricked.

Clickbait creates curiosity but doesn’t deliver on its promise.

14 Curiosity Gap Email Subject Line Examples

Let’s look at examples of various types of email subject lines and how you can use the curiosity gap technique in them:

The question subject line

What Is Outsourcing And How Can It Boost Your Productivity?

  • What: outsourcing
  • Who: you
  • Promise: boost your productivity

Can’t Decide What To Blog About? These Ideas Will Help

  • What: blog topics
  • Who: you
  • Promise: these ideas will help you generate blog topics

The ‘How to’ subject line

How To Determine What Your Time Is Worth

  • What: the value of your time
  • Who: You
  • Promise: that you’ll be shown a method for determining how much your time is worth

How To Use One-Time Offers (OTOs) To Quickly Boost Sales

  • What: use one-time offers (OTOs)
  • Who: You (implied)
  • Promise: make more money

The scarcity subject line

20% Off Ends Tonight!

  • What: a 20% discount
  • Who: You (implied)
  • Promise: discount ends soon, but if you act now, you can save 20%

Issue Preventing Payment – Please Update Your Account Information

  • What: an issue preventing payment
  • Who: You (implied)
  • Promise: fix the issue and get paid

The announcement subject line

Doors Are Open! Join DIY Club and Get the WordPress Help You Need

  • What: DIY Club membership
  • Who: You
  • Promise: get the help you need with your WordPress website

Introducing Wix SEO Fix! Get Your Wix Site Indexed and Ranking

  • What: DFY SEO service
  • Who: Wix website owners
  • Promise: get your website indexed and ranking in search results

The number subject line

7 Ways to Get Your Ideal Client to Say Yes to Your Offer

  • What: 7 ways
  • Who: your ideal client
  • Promise: say yes to your offer

21 Helpful Footer Tutorials for Divi

  • What: 21 tutorials
  • Who: Divi site owners
  • Promise: Help with footers on your website

The surprise subject line

Why Local Businesses Don’t Really Need a Website

  • What: a website
  • Who: local businesses
  • Promise: local businesses can succeed without a website

Keep Google’s Eyes Off Your Content: When, Why, and How

  • What: Google’s web crawler
  • Who: You
  • Promise: you’ll learn how to keep your content from getting indexed, when that is desirable, and why

The personalized subject line

Suzanne, this secret code is for your eyes only…

  • What: secret code
  • Who: You (whatever your name is lol)
  • Promise: exclusivity

Suzanne, unlock your Smart Driver discount and FREE gift!

  • What: discount and free gift
  • Who: You (whatever your name is lol)
  • Promise: that you can get a discount and a free gift

Curiosity Creates Clicks, No Matter the Type of Content

The crucial element in making curiosity work is to respect your reader’s intelligence.

Every time you pique their curiosity, make a promise, and then deliver on that promise, you increase their confidence in you, your brand, and your offers. Give them a positive experience and they’ll reward you with their attention. Play them for a fool, and you won’t have much of an audience for long.

Using the curiosity gap technique can significantly increase not only your email open rate but your conversion rate, too. On sales and landing pages, use it in your subheads, form titles, and calls to action and your bounce rate will improve.

Delivering on your promise is even more critical when advertising or promoting on social media platforms, if only because that’s where your audience sees so much clickbait.

Combine the curiosity gap technique with your knowledge of your audience and you’ll be writing irresistible headlines every time!


curiosity gap in email subjects infographic
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