5 subject line styles that will increase your email open rate

by | Mar 29, 2021 | Analysis, Public Relations

You finally chose the right email marketing tool, crafted your sequences, and got ready for cash to come rolling in. But then… nothing.

No one’s reading your emails, no one’s opening their wallet, and no one cares. Fortunately, there’s a simple solution to your problems. Optimized email subject lines.

Email subject lines get the reader to open your email. By optimizing them, you can increase your chances of conversion by 1000 percent.

We’ll walk you through five email subject line styles that you can easily adapt to your business and will get your audience opening every single email.

Five styles for catchy email subject lines

Subject lines can exhibit several features at once. We’ve categorized the styles based on the most prominent feature.


Direct subject lines tell the reader what to expect inside. We can divide them into two subcategories. Direct offer subject lines are straightforward and reveal the sender’s offer:

5 subject line styles that will increase your email open rate

The goal isn’t to be creative or funny but to relay the most important information about the offer in an easy-to-understand way.

The reader knows exactly what deal they get, but they might not know the benefits of the offer or how it improves their life.

Our example subject lines only imply the benefits:

  • Get stuff done faster
  • Pamper your lashes and save money

They’re not the focus of direct-offer subject lines. They’re covert.

Direct benefit subject lines emphasize the benefits the reader gains:

5 subject line styles that will increase your email open rate

Benefits work best when they’re specific, like in the third example. The reader is told exactly how much they could earn. Compare that to the last example. While it’s enticing, it’s not as clickable as the subject line with the number in it.

Benefits should also be emphasized with your target audience in mind. Your product (or whatever you’re promoting) might have a ton of benefits, but your job is to find the one that your audience yearns for the most.


Proof-driven email subject lines work like a charm with highly aware customers. They usually contain exact numbers and social proof:

                  [Case Study] How Melissa earned $17,859 in a month

The purpose of proof-driven subject lines is to convince the reader of two things: a) other people are already getting real results; and b) they can get these results too.
Notice the odd number in the example subject line? It’s there for a reason. Odd numbers are more believable. They make the results seem more real. Imagine if, instead, the subject line read:

[Case Study] How Melissa earned $17,000 in a month

Not as convincing, right?

Urgency and scarcity

Urgency-driven subject lines trigger FOMO. They encourage the reader to act promptly, usually before the deal expires:

5 subject line styles that will increase your email open rate

The subject line sets a deadline for the reader. It can be anywhere from a few hours to a few months.

Urgency is closely related to scarcity. One affects the other: urgency produces a sense of scarcity. Scarcity produces a sense of urgency. Most marketers create scarcity with limited time or seat offers.

Along with FOMO, scarcity creates a sense of exclusivity because not everyone will be able to get the offer. This further motivates the reader to grab the deal asap.

Pro tip: Don’t create false limited offers. At least a few people will catch on and this could ruin your brand’s reputation for good. It’s not marketing—it’s lying.


Curiosity-driven subject lines rely on curiosity gaps, which is a gap between what the reader knows and what he’d like to know.

It’s the job of the subject line to create the gap and the job of your body copy to close it (unless you’re sending your reader to another piece of content):

5 subject line styles that will increase your email open rate

You can trigger curiosity by using controversial statements or implying that the email offers some backdoor secrets. The Guardian went for the first option. Other examples create a sense of mystery by using power words and phrases:

  • Incredible Results!!!
  • Illegal
  • ONE secret
  • Surprise inside


Single-word subject lines are powerful for two reasons:

  1. Your email stands out. Chances are your reader’s inbox is cluttered with promotional emails. Most of them have longer subject lines (app. 50 characters), so a single word will immediately grab your reader’s attention.
  2. Curiosity. Your reader will want to know the story behind the word in your subject line if you play your cards well.

You can use something straightforward like the recipient’s name or a simple hello. Or you can make your email subject lines even more enticing by using power words, such as “free”, “secret”, or “gift”.

The takeaway

Many businesses try to sell the click with their email subject lines when their sole purpose is to get the reader to open the email—not to take the action suggested in the email. They’re trying to kill two birds with one stone, which usually ends up with both birds fluttering away.

Be smarter. Be laser focused. Use email subject lines only to get your email opened and use our guidelines for best results.

Torge Janiesch
Torge Janiesch has been an Email Marketing Expert since 2011. He is the Co-Founder of the website emailtoolreviews.com, where he makes in-depth reviews of email marketing softwares. When not nerding out, he loves to travel, create beautiful DIY interior designs and pursue his interest in personal development.


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