12 Types of Email Subject Lines That Will Increase Your Open Rates

12 Types of Email Subject Lines That Will Increase Your Open Rates

Last updated on by Ted Vrountas in Conversion Optimization


“Please put us out of our misery.”

That award-winning email subject line, written for a UK financial management company called Money Dashboard, ran as part of an A/B test against a previously high-performing email.

It was a Hail Mary attempt at getting a group of inactive email subscribers reengaged. It went against everything the senders knew about email marketing best practices. So you can imagine their shock when it outperformed the reigning subject line by a long shot.

This picture shows marketers how Money Dashboard used desperation in its email subject line to increase its open rate.

Compared to the former high achiever, “What’s your opinion here [first name]?”, it generated over 100% more opens and 228.5% more clicks at a 99% level of significance. But why?

What makes the average person, whose inbox gets stuffed with 147 messagesg per day, choose to open one email and ignore another?

We dove into some reports, case studies, and inboxes to find out — to help you figure out how to get your subscribers to open yours during your next email campaign.

The purpose of email subject lines

A good email subject line is like a good landing page headline — without one, your audience isn’t going to read the rest of your content.

If your subject line isn’t compelling, your subscribers won’t open your email. If they don’t open that email, they won’t see the links to all the new products you’ve launched, or the blog post you just wrote. If they don’t do that, your campaign’s a goner.

In short, a good email subject line convinces readers to open your email. It gets them excited about what they’re going to learn, or become, after they look through it — and it uses language that compels them to click through.

How many people click through their emails?

Just because 72% of people say they prefer to be contacted by companies via email over any other channel doesn’t mean that they’re going to open every message you send them. In fact, looking at recent open rate data from MailChimp, you might think people don’t want to see your emails at all.

In most industries, around 1 in 5 (20%) people who get a business email will open it, with some companies seeing open rates as low as 14%. So how do you convince the other 4 out of 5 to read your email?

With a compelling email subject line.

What’s in a good email subject line?

Some say you shouldn’t start your email subject line with “How to.” Others disagree, adding that funny, mysterious, and one-word lines get opens.

While we found a variety of advice on getting your marketing messages read, there were several that appeared over and over again on industry blogs.

We couldn’t help but notice their similarity to best practices suggested decades ago by legendary copywriter John Caples, who was known for his ability to craft irresistible headlines.

What follows is some advice from the headline maestros, combined with tips from some of the most knowledgeable authorities in email marketing, to convince the other 80% of your subscribers to click through.

Email subject lines that work

1. ”How to”

It might seem boring and unimaginative, but the “How to” subject line is a classic.

It’s effective because if offers your prospect a powerful guarantee: What they’re about to read is going to teach them something. Here’s a great example from Salesforce:

This picture shows how Salesforce uses a "how to" email subject line to increase their open rate.

Not only does this email offer you an opportunity to learn something, but it takes advantage of a few other psychological principles that we’ll touch on next.

2. Self-interest

It’s not just the words “How to” that make the email subject line from Salesforce above so clickable, but the appeal to our inherent self-interest. Remember that, on the whole, people strive to be better.

We want to learn how to make more money, improve our memory, and find success with the opposite sex. It’s these things that motivate us to open some of the emails you’ll see below, like Grammarly Insights’ weekly progress report email, which helps users of the service improve their writing.

This picture shows marketers how Grammarly uses self-interest in its email subject lines to maximize its open rate.

Some more self-interest headlines:

The self-interest “how to” headline has been around since the early days of modern advertising. If it seems like it’s been used a lot, that’s because it has, and for a reason: it works.

Look at the email below. If you’re telling us you wouldn’t open it to find out where to find the cheapest airfare to fly to the places you’ve always wanted to visit, we don’t believe you.

This picture shows marketers how Airfarewatchdog uses self-interest in its email subject line to maximize its open rate.

3. Quick and easy fix

There’s something else about that first Salesforce email that makes it almost irresistible to open. But before we get to it, let’s briefly touch on a psychological idea we know to be true: humans are lazy. Our brains are wired to look for the highest return for the lowest investment.

We don’t want to work out for months or years to get that six pack — we want the shortcut. We want to take diet pills, and use weird electric belts that tone our midsections instead.

We don’t want to accrue wealth over time by correctly saving and investing. We want a fortune, and we want it now. So instead we do things like spend our life savings on lottery tickets in the hopes of winning big.

It’s for this reason that when we see words and phrases like “in 15 minutes” in the Salesforce email above, and “secrets” shown in the AWAI email below, we’re compelled to read more. We expect to get small bits of information, or “secrets” that will have a significant positive impact on our lives immediately.

This picture shows marketers how The Writer's Life uses a "quick and easy" fix in its email subject line to maximize their open rate.

Take a look at some of the phrases from the subject lines above:

One subject line from the IMPACT Blog even goes so far as to mention laziness right in it! If convincing someone they can use their lazy tendencies to achieve success won’t get them to open an email, we’re not sure what will.

4. Scarcity

Scarcity in marketing capitalizes on our fear of missing out on something — a fun event, a valuable resource, and in most cases, a good deal. Check out the email from United Airlines below:

This picture shows marketers how United Airlines uses scarcity in its email subject lines to maximize its open rate.

June 30th was one of the “Final days to earn 50,000 bonus miles.” Your inbox is likely jam-packed with emails like these:

Similar to the “how to” subject line, if it seems like scarcity is overused in marketing, that’s because it works. We use it ourselves to drive signups:

This picture shows how Instapage uses scarcity and savings in its email subject lines to maximize its open rate and sales.

When using scarcity, however, it’s important not to come across as too salesy. Certain words and phrases that marketers use to convey a limited-time discount can trigger email spam filters, and get your message sent straight to the junk folder.

5. Comparison

Who knew psych 101 would be so useful in helping you craft compelling email subject lines? This time, we refer to a lesson on social comparison theory. According to Psychology Today:

“Social comparison theory states that we determine our own social and personal worth based on how we stack up against others. As a result, we are constantly making self and other evaluations across a variety of domains (for example, attractiveness, wealth, intelligence, and success). Most of us have the social skills and impulse control to keep our envy and social comparisons quiet, but our true feelings may come out in subtle ways.”

Based on that theory, it should come as no surprise that Experian’s subject line starting with “See how you measure up,” and Formstack’s line ending with “do you relate? ” are hard to resist clicking through.

6. Curiosity

Curiosity didn’t just kill the cat and compel Pandora to ruin life for the rest of us (thanks, Pandora). It’s also a valuable marketing tool — one that often drives us to take action.

Curiosity is the reason for the viral success of news publisher Upworthy. Even if the “curiosity gap is closing,” meaning we’ve become immune to over-hyped headlines like “This young inventor’s brilliant device could remove tons of garbage from our oceans,” and “It looks just like another picturesque view, but the truth is far deadlier.”

However, curiosity shouldn’t be abandoned altogether. Copyhacker Joanna Wiebe used it to generate 927% more signups on a pricing page. When used responsibly and sparingly, it can produce similarly powerful results for email.

This picture shows marketers how Orbitz uses curiosity in its email subject lines to maximize its open rate and sales.

When curiosity is used incorrectly, however, it can leave your subscribers scratching their heads. Take the following email subject lines for example:

Why do we care about “This week’s most popular homes”? Why would we want to “hear a story” that we don’t know we’ll even care about? What is the “‘Forehead Slap’ Test” and why should we care if my copy passes it?

It’s important to always remember that your prospects have limited time on their hands. If they can’t tell from your email subject line that opening your message is going to be worth it, they’ll either ignore it or send it directly to the trash.

7. Question

Questions engage readers. When coupled with another one of the headline types above, they’re even more powerful, like the one from Mindy McHorse below: “Ted, want to quit your job and get paid to write?”

8. Authority

Authority is a powerful driver of conversions on landing pages, and it can be used elsewhere, too — including email subject lines. This one from Copyblogger compels its readers to click through by citing an interview with a well-known digital marketing entrepreneur, Moz’s Rand Fishkin:

While it doesn’t come out and promise any valuable insight, it’s implied. If you’re not in the digital marketing industry, replace Rand Fishkin’s name with one of your idols and ask yourself, “Would I open this?”

Our guess is yes.

The same could be said of this email from Glassdoor:

This picture shows marketers how Glassdoor uses authority in its email subject lines to maximize its open rate.

“10 Companies Hiring Now” and “10 Fortune 500 Companies Hiring Now” are two very different subject lines. The first might conjure images of working at the hardware store down the street, or the furniture retail outlet in the suburbs. But when we see “Fortune 500,” we imagine working for big, prestigious companies, with a comfortable salary and excellent benefits. That’s the power of authority.

9. Straightforward

When you have something valuable to offer, sometimes it’s best just to come out and say it. Did you just finish compiling a year-long report on the state of the industry? Did you finish some templates that your email subscribers can use to better their marketing? Let them know.

If it’s truly a valuable resource, you won’t need to get fancy with curiosity or add an authority booster to your subject line. A straightforward one, like the those listed below, will do just fine.

10. Exclusivity

Are your subscribers part of an exclusive club? Remind them, like the email subject lines below do:

People like feeling special, even in their inboxes. Making them feel like they’re in on something that few else are could be what gets them clicking through to your promotional email.

11. Case study

People like case studies for two reasons:

They provide proof that a technique or strategy works
They often offer a step-by-step, replicable process that readers can use to achieve the same results

So, when you create a case study that combines scientific proof with self-interest like the ones below, make it known in your email subject line:

This picture shows marketers how Derek Halpern uses a case study in its email subject line to maximize its open rate.

12. Share news

News subject lines take advantage of our inherent desire to be in the know. Even if you don’t follow mainstream news outlets, chances are you stay up-to-date on topics of your interest in some way. This could be:

So when you have news to share, whether it’s about your industry, or even your own products, let subscribers know the way the following brands do in their email subject lines:

This picture shows marketers how Vitamin Shoppe uses "news" in its email subject lines to maximize its open rate and sales.

What’s your next email subject line?

What are your favorite email subject line strategies? Did you write any of the ones above? Let us know how it performed in the comments, then begin creating a landing page for your email campaigns using Instapage’s designer-friendly software.

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