Email marketing is getting harder every day.

Between email service providers (ESPs) changing their spam filters and competitors vying for your buyers’ limited attention, it’s never been harder to get noticed.

But, fortunately, there’s one thing that never changes:

Why customers do what they do.

In today’s fast-paced digital age, getting—and more importantly holding—your reader’s attention isn’t just a nicety; it’s a necessity…

…and there’s no better way to do that than by writing psychology-driven email subject lines.

So, today, rather than give you templates to model or catchy email subject lines, I want to show you how to utilize key principles of influence (or “persuasion triggers”) to write tantalizing subject lines that get more readers to open your emails.

But before I do…

Download our free email marketing “fundle” (like bundle, but more fun)

Writing email campaigns that get opened is TOUGH. To help, I’ve put together a swipe file of 41 top-performing emails. Plus, all the campaigns featured below and a few other goodies (don’t tell anyone).

Free Downloadable Bonus
Get access to our e-commerce email marketing bundle and improve your email open rate today (includes 3 emails not featured in the post).

What is a good email open rate?

Before delving into persuasion triggers, it’s worthing familiarizing yourself with a few important email marketing benchmarks…

…and that means knowing the average open rate for your industry.
According to a recent study by SignUpTo, the average open rate across all industries is 24.79%:

Average Email Open Rate

This, of course, fluctuates greatly from industry to industry (and report to report, for that matter).

A study by GetResponse, however, showed a marginally lower average open rate at 21.73%:

Average Open Rate for All Industries

Taking another approach, MailChimp analyzed the average email open rate by company size, rather than industry, and found similar results to GetResponse:

Mailchimp Average Email Open Rate

So, if you’re getting above average opens for your campaigns—or you’re not and you want to do something about it—the following eleven persuasion triggers will help you write better subject lines and get higher email open rates.

Get more email opens with these 11 proven persuasion triggers

1. Personalization

In 1936, Dale Carnegie wrote one of the most influential books of all-time, How to Win Friends and Influence People.

In it, Carnegie revealed one of his simplest, yet most important findings after years of researching human behavior:

“A person’s name is to that person the sweetest and most important sound in any language.”

It’s no surprise, then, many marketers include the recipient’s name when writing email subject lines.

In fact, emails with personalized subject lines are 26% more likely to be opened and many marketers have even found a 73% increase in revenue per email.

Email Subject Line Personalization

Ramit Sethi, from I Will Teach You to Be Rich, often uses the recipient’s name in his email subject lines:

Ramit Sethi Email Subject Line Example

Using the recipient’s name in an email subject line doesn’t just appeal to reader’s ego—it produces compliance with a request.

Why?

Because singling out an individual makes them accountable.

As Robert Cialdini writes in Influence: The Psychology of Persuasion,

[When making a general request for help] pick out one person and assign the task to that individual. Otherwise, it is too easy for everyone in the crowd to assume that someone else should help, will help, or has helped.

By simply including my name in the email subject line and asking for my help, I felt more compelled to open Ramit’s email—and comply with his request.

(Sidenote: Yes, I bought his book and it made The Wall Street Journal bestseller list. Coincidence? I think not.)

Granted, asking for a name on your lead form can affect your optin rate (depending on who you ask), but one thing’s for sure: it can increase your open rate.

ProTip. If you are asking for a name, always have a fallback in place in the event it’s left blank. No one wants to be addressed “Hi [NAME].”

2. Scarcity

We all like to believe we’re rational beings and make the right decisions for ourselves.

But you probably know, that’s not always the case.

In truth, many of our purchasing decisions are influenced by our fear of potential loss.

Further, to paraphrase Cialdini, we’re more motivated by the thought of losing something than by the thought of gaining something of equal value.

In other words, it’s not that we’re driven by our desire to gain a new purchase (like one would expect). Rather, we’re driven by our fear of missing out (FOMO).

Scarcity is often overused and misunderstood. So here’s a brief refresher on the different types of scarcity with examples of when and how to use it in email marketing.

i. Scarcity of availability

Marketers are cognizant of our fear of missing out.

It’s why they remind consumers to “Hurry! While stocks last!” and why they’re warned, “Once they’re gone, they’re gone.”

Violet Grey explicitly mention limited availability of certain items of stock in their emails for this very reason:

Violet Grey Email Subject Line Example

If you have limited availability of a particular item, don’t be afraid to tell your customers.

They’re not mind readers.

ii. Scarcity of cost

Let’s face it:

We LOVE coupons.

And if you’re like 93% of retail consumers, you redeemed one recently to buy a product you always use at a better price.

While discounting goods is an effective way for retailers to increase revenue (when done correctly), it’s particularly effective when it’s paired with urgency.

After all, we all want to avoid pain and gain pleasure. And if we think we’ll experience pain from NOT taking action, we’ll make a purchase.

Crocs utilize scarcity of time and money in their email subject lines to boost revenue:

Crocs Email Subject Line Example

Scarcity is clearly a powerful principle of persuasion.

But be warned:

You need to use it ethically.

When we feel like we’re subjected to false scarcity (among other overused marketing tactics), we’re unlikely to buy.

As one study found, “When consumers interpreted scarcity claims as a sales tactic, the positive effect of scarcity claims on product evaluation would be diluted.”

Consumers are irrational—perhaps even predictably irrational, at times—but they’re not foolish.

Don’t overdo it.

Some eCards Irrational Behavior

3. Authority

There’s a reason we pull over when we see a flashing beacon in our rearview mirror. Or, why we’re inclined to take medical advice from a person with letters after their name (rather than a stranger):

We have a natural tendency to obey authority.

What’s interesting, though, is, in marketing, consumers aren’t always driven by authority, alone. Rather, they’re driven by their perception of authority.  

Specifically, who they believe has authority.

One way to demonstrate authority is to “borrow” it from other experts. Here’s a good example from a recent email from Ryan Robinson:

Ryan Robinson Email Subject Line Example

We can create authority through association. If you’re involved with the brightest minds in your industry, it will only reflect positively on you.

Demonstrating a result your audience is trying to achieve is another way of building credibility in the eyes of your audience.

Jon Morrow helps his audience generate more traffic and often refers to his own experiences to back up his claims:

Jon Morrow Email Subject Line Example

But what if you don’t have any authority?

You can do what Bryan Harris often does and tell the reader EXACTLY what you want them to do.

In fact, Brian begins many of his email subject lines with power words, inviting the reader to take a certain action:

Bryan Harris Email Subject Line Example

One caveat, though, is if you don’t have existing credibility with your audience, demonstrating authority can backfire (after all, no one likes being told what to do).

Use it wisely.

4. Curiosity

How often were you warned as a child, “Do NOT push that button”?

Now:

How often did you actually obey your parent’s wishes?

Not often, right?

If not, who can blame you: curiosity is a powerful motivator.

Our need to bridge the gap between what we know and what we want to know is what we refer to as the curiosity gap. In email marketing, when we’re presented with a compelling reason to click-through (or NOT click-through), we can’t help but satisfy our curiosity.

Mary Fernandez creates intrigue in her readers by telling them what NOT to do:

Mary Fernandez Email Subject Line Example

Mary knows having an email inviting you NOT to open is too good to ignore. And as you can tell from the above image, I couldn’t help myself.

To build curiosity into your subject lines, you can ask readers an intriguing question (Curioos):

Curioos Email Subject Line Example

Or, like Fab, you can make a promise that offers an immediate payoff upon opening:

Fab Email Subject Line Example

Bottom line:

Always deliver on what you’re teasing. No one enjoys an unfulfilling cliffhanger.  

5. Utility

In 2011, Jonah Berger, a professor at the Wharton School of the University of Pennsylvania, carried out a research study analyzing why certain articles go viral.

Among his discoveries, Berger discovered useful content is shared more often.

In his book, Contagious, he writes,

People like to help others, so if we can show them how our products or ideas will save time, improve health, or save money, they’ll spread the word.

While the above is applicable to writing headlines, the same principle can be applied to email marketing (after all, headlines are to content what email subject lines are to emails).

The goal, with your campaigns, remember, isn’t just to increase brand awareness or boost revenue; it’s to add value to your audience.

And there’s no better way to do that than creating useful content and notifying readers of such with an appropriate subject line.

Brian Dean always emails his reader actionable content that they can immediately apply after reading:

Brian Dean Email Subject Line Examples

Providing value isn’t just applicable to marketers, though. In fact, it’s especially important in industries like e-commerce, where most campaigns are revenue-related.

Beardbrand varies their emails by offering content that solves common challenges for their audience:

Beardbrand Email Subject Lines Examples

Rather than regularly send promotional campaigns, vary it with helpful resources, videos and other actionable content. Your audience will thank you for it (and when varied with promotional emails, it will make a noticeable difference to your bottom line.)

6. Numbers

You probably already know the effectiveness of adding numbers to headlines.

One study by Conductor found headlines with numbers tend to generate 73% more social shares and engagement.

Conductor Overall Headline Preferences

Further, in a meta analysis of more than 300 articles about online learning, Abreena Tompkins found “grouping information in parcels of three or five can help people absorb information better.”

In other words, headlines with odd numbers tend to perform better than even numbers.

The thing is…

Writing number-driven headlines doesn’t just apply to headlines; it applies to email subject lines, too.

Check out this recent email I got from Derek Halpern:  

Derek Halpern Email Subject Line Example

His email not only creates curiosity (who would spend ¢139,614.18 on ONE Facebook ad?), it uses an ultra-specific number to capture the reader’s attention.

Numbers are powerful…

But specific numbers are even more powerful.

Use them often.

7. Social proof

Commonly associated with customer testimonials, social proof is one of the oldest persuasion triggers in a marketer’s toolkit…

And most effective.

Simply put, when we’re indecisive, we’re more likely to look to and accept the actions of others as the way to behave.  

According to Cialdini who popularized this phenomenon, “The greater the number of people who find any idea is correct, the more the idea will be correct.”

If you have an item that isn’t budging—or is, but you want to push it harder and faster—why not inform your audience how popular it is?

When opening enrollment for his flagship program, SEO That Works, Brian Dean uses social proof to nudge prospective buyers into becoming customers:

Brian Dean Email Subject Line Example 2

(Note: Do you think it’s a coincidence Brian used an odd number?)

Social proof email subject lines are only as powerful as the testimonials that accompany them, so remember to backup everything you claim in the subject line in the body of your email.

8. Framing

In 1981, Amos Tversky and Daniel Kahneman investigated how different phrasing affected participants’ responses to a choice in a hypothetical life and death situation (Source: ScienceMag).

Participants were asked to choose between two treatments for 600 people affected by a deadly disease. This choice was then presented to subjects either with positive or negative framing:

  • If Program A is adopted, 200 people will be saved.
  • If Program B is adopted, there is 113 probability that 600 people will be saved, and 213 probability that no people will be saved.

Guess what happened?

Program A was chosen by 72% of participants when it was framed positively.

Outcomes like the above are due to the framing effect: our tendency to react to a particular choice in different ways depending on how it is presented (e.g. as a loss or as a gain).

In marketing, framing is common when it comes to pricing a product or service. You will often see tiered pricing on a pricing page, but you can also leverage it in your marketing campaigns.

In one of his recent emails, Stu McLaren promoted Michael’s Hyatt’s $197 training program, 5 Days to Your Best Year Ever, by framing it $0.54 per day:

Stu McLaren Email Subject Line Examples

The takeaway?

If you’re writing an email offering a coupon, don’t be afraid to specify exactly how much the reader will save. There’s a big difference between getting 30% off today and saving $147.27 before 11:59 p.m.

9. Reciprocity

Reciprocity is a powerful principle of persuasion because it works closely with the foot in the door technique: the tactic of starting with a little request in order to gain eventual compliance with related larger requests.

In other words, if a prospective buyer complies with a request (like opting in for a lead magnet, starting a free trial, buying a tripwire product), they’re more likely to comply with a larger request down the line (like buy a high-ticket item).

Like many subscription box services, Dollar Shave Club offers new members their first box free for this very reason:

Dollar Shave Club Email Subject Line Example

Dollar Shave Club is able to offer so much value up front because they know their customers will reciprocate down the line and become lifelong customers.

Moreover, while it’s not explicitly mentioned in the body copy, Dollar Shave Club imply urgency by writing “Don’t miss your FREE month.” That’s the power of compelling e-commerce copywriting.

In a world where many readers are bombarded with promotional emails, don’t be afraid to offer value first. Oftentimes, it will come back manyfold.

10. Salience

Take a look at the following email subject lines.

Which ones (if any) capture your attention?

Barkbox Email Subject Line Examples

The ones with the emojis, right?

Why?

Because emojis in email subject lines create salience.

According to a report by Experian, 56% of brands using emoji in their email subject lines had a higher unique open rate.

Emojis aren’t the only example of salience. Marketers CAPITALIZE certain catchy words for similar reasons (although it’s often overdone).

My favorite way?

Vary the length of your email subject lines.

Salience in Headlines

As Nick Kolenda writes, “If most titles are long, submit a short title. If most titles are short, submit a long title. You’ll create saliency from the size difference—which should capture attention.”

11. Liking

You probably won’t be surprised to learn we prefer to say yes to the request of people we know and like.

In Cialdini’s words,

We like people who are similar to us. This fact seems to hold true whether the similarity is in the area of opinions, personality traits, background, or lifestyle.

What you might be surprised to learn, however, is you can use liking in your email subject lines to trigger liking and build commonality even faster.

Using words like “totes,” Kate Spade speak their target market’s language to create familiarity:

Kate Spade Email Subject Line Example

A word on jargon, though: like many principles of persuasion, don’t overuse it. If you’re selling electrical items, for instance, outline the features in clear, easy-to-understand language, but sell the benefits in a way that resonates with your audience.

Download our free email marketing “fundle” (like bundle, but more fun)

Writing email campaigns that get opened is TOUGH. To help, I’ve put together a swipe file of 41 top-performing emails. Plus, all the campaigns featured below and a few other goodies (don’t tell anyone).

Free Downloadable Bonus
Get access to our e-commerce email marketing bundle and improve your email open rate today (includes 3 emails not featured in the post).

The best email subjects lines come from you

If you want to get noticed in readers’ inboxes, writing eye-catching email subjects and following best practices is crucial.

And utilizing the above principles of persuasion will no doubt help.

But’s it’s not everything.

What’s more important is what happens after readers open and read your emails.

That’s where the real magic happens.

If you focus on continually offering value, delivering on your promises and cultivating a healthy relationship with your audience, having to think of “good” email subject lines will be the least of your concerns.  

Which persuasion trigger will you use in your next marketing campaign? Leave a comment below.

Sam Thomas Davies
Sam is the content marketing manager at Sleeknote. His specialties include copywriting, content marketing and SEO. When he’s not helping ecommerce business owners turn visitors into subscribers, he can be found practicing guitar, reading, and playing hide and seek with his wife.

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