Email subject lines tend to be prime real estate for marketers.

Because digital marketing is predicated on accruing email subscribers – and subject lines play a big role in determining whether those subscribers open your emails – compelling people in just a few words poses a big challenge and responsibility for anyone creating emails.

Brands understand this – so much so that many subject lines tend to overpromise and underdeliver on content. Marketers think, “People will see the value once they open the email. So let’s do whatever we can to influence opens.”

However, deceptive subject lines can break subscribers’ trust. Even if there is value within those emails, if your email doesn’t close the loop on the promises of your subject line – without having to click through – you risk misleading subscribers.

Worse, deceptive subject lines violate spam laws and could significantly impact your sender reputation, a critical factor in how ESPs filter your messages.

These bad habits also have a significant impact on your team. If open rates are valued above trust and brand equity, opens will also be what are celebrated. Unfortunately, opens don’t necessarily suggest long-term benefits or organisational value, so as a result, your team winds up stuck in a cycle of meaningless growth, valuing and celebrating the wrong factors.

Instead, you need to craft emails that are so useful that their value is naturally reflected in the subject lines. No tricks, gimmicks, or “open at all costs” mentality.

To do so, focus on utility and curiosity.

It’s about people, not your brand

Subject lines should focus exclusively on the customer. People don’t care about what you’ve learned or discovered unless it impacts them. People don’t value products or services; they value what a product or service enables them to do.

People crave utility and tangibility, so you need to deliver both in every email. Forget about first name personalisation. Personalise the subject matter, not the subject.

I joined the Dollar Shave Club last fall, and right before my first box shipped, I received an email with the subject line “Your first box is about to ship. Toss more in.”

This was pretty pertinent information for me. Naturally, I opened it.

Inside were four product suggestions, including a shave butter I had never tried. I wouldn’t normally purchase shave butter, but at $4.99, I thought, “Why not? One less thing I have to remember at the store.”

Dollar Shave Club knows its users value convenience over features. Its razors don’t have eight blades, a battery, or other gimmicks. They’re just razors. But they’re delivered to customers’ doorsteps every month for less than they’d pay in the store: convenience over features.

This email, from the subject line through the body copy, stayed consistent with this message. That’s personalisation. Dollar Shave Club doesn’t need to use my name anywhere in the email. Instead, it knows why I buy and uses this to improve my experience and increase sales.

Opening a curiosity gap

One of the harsh truths of email marketing is that the inbox is not a meritocracy. Great emails are ignored every day because of generic subject lines. While your email might actually be packed with utility, if the subject line is uninspired, your subscribers are likely to follow suit.

While there are many methods of combating this problem, one of the most effective I’ve found is one of the oldest triggers of influence used in marketing and advertising: curiosity.

Curiosity is like an itch; once someone feels it, it’s hard to ignore. Instead of writing subject lines like “How to improve your meta description and boost search rankings,” you would use something like “This one line of copy could boost your search rankings.”

Which do you think would perform better?

This is actually a widespread tactic used to market a lot of things. Just look to your local 11 p.m. news for evidence. You might hear something like, “These five items in your medicine cabinet could be causing you cancer. Stay tuned at 11.”

Heavy stuff. But it just might get you to tune in.

Joanna Wiebe, founder of Copy Hackers, demonstrated the effectiveness of the curiosity gap in an email subject line she worked on with Quick Sprout that saw super-high open rates. The subject line?

“Boom! This is how you get traffic…and convert it.”

This email saw a 102% open rate. (Yes, you read that correctly.)

But here’s the most important part about opening curiosity gaps in email subject lines: you must close them! This is critical. Don’t make readers open the email, click through to your site, and follow several steps before getting around to closing that curiosity gap. This will adversely affect your overall engagement success.

Marketers with an “open at all costs” mentality will think otherwise, but you’re better than that. If you’re here reading this article, you feel some degree of responsibility to create a great experience for your subscribers.

Hang onto this. It’ll serve you and your subscribers well.