7 Proven Tips to Write Catchy Email Subject Lines That Convert

An email is only ever as good as its subject line.

Because an unopened email may as well have no content.

An email subject line motivates people to open the email.

It’s as simple as that.

In fact, marketing experts suggest that you should spend more time crafting your subject line than the email itself.

And, crafting strong subject lines is even more vital in nurture campaigns.

What is a nurture campaign?

A nurture campaign is a series of emails sent in a specific sequence intended to nurture a relationship with your prospects or customers. While goals may vary, the common goals of nurture campaigns are to grow trust, build brand recognition, motivate subscriptions, registrations, or drive sales. Each email in a nurture campaign works best when it builds on the one that came before and contributes some new value to the reader. So, the more messages a person opens, the more compelling (and successful) your nurture campaign is likely to be.

Let’s look at subject line best practices that will improve email open rates and lead to stronger, more effective emails, nurture campaigns, and better email marketing.

7 proven tips to write catchy subject lines:

1. Write subject lines that generate curiosity.
2. Craft subject lines that leverage urgency.
3. Use power words in subject lines.
4. Highlight value in subject lines.
5. Include data in subject lines.
6. Set proper expectations with subject lines.
7. Keep subject lines short.

Tip #1: Write subject lines that generate curiosity.

Generating curiosity is one of the most important tasks of any email subject line.

The best email subject lines create enough curiosity to get you to look inside.

It’s not enough to have a large email list. If your audience isn’t curious about what’s inside, they probably won’t open your message.

Olivia Allen explains,

…it’s good to maintain some sense of mystery — especially if it pique’s the recipient’s natural curiosity and interest. Because they [enigmatic subject lines] require opening the email to get more information, they can result in, well, a higher open rate.

It’s even more important to increase open rates for emails that kick off a nurture campaign.

If the recipient isn’t curious enough to open their first few emails, they’re less likely to open subsequent messages in the campaign.

In fact, curiosity is important whenever you try to summarize something. The same principles apply, for example, if you’re writing a business plan. You can write a great business plan but unless people read it, you won’t make an impression. The summary section of a business plan plays an important role. The better the summary, the more curiosity it generates, and the more likely an investor will read your business plan.

That’s precisely how email subject lines work.

So, how does one generate curiosity with email subject lines?

It helps to be specific enough that the reader knows that the information is relevant to them. But, you don’t want to give everything away. As Allen pointed out, a sense of mystery is compelling.

Many of the techniques that we’ll address below (urgency, power words, implied value, and data) are effective because they also help drive curiosity.

Write subject lines tailored to drive curiosity to improve open rates for individual emails and nurture campaigns.

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Tip #2: Craft subject lines that leverage urgency.

Urgency is one of the core psychological tenets of marketing.

Urgency motivates people to act – fast.

In fact, urgency often acts as a shortcut to action – overriding the brain’s analytical part and leading to impulsive decisions.

So, subject lines that create urgency can be powerful.

Here are some email subject line examples that reflect urgency:

• Limited edition: Only 200 available!
• Your coupon is about to expire.
• This discovery could save your life.
• Act now while supplies last!
• The best price of the year – sale ends today!

All of these subject lines create a fear of missing out (or FOMO), also known as “loss aversion.”

Whether the reader is about to miss out on a discount, important information, or a specific item, they stand to lose something.

This can result from real scarcity (a limited number of items) or contrived scarcity (like an arbitrary sale deadline). But, any form of scarcity can create urgency and action.

For example, a study on The Psychological Effects of Perceived Scarcity on Consumers’ Buying Behavior revealed that:

…scarcity communicated by the retailer threatens consumers’ freedom, thus triggering psychological reactance and encouraging them to take immediate actions like in–store hoarding and in–store hiding…

If scarcity can motivate people to physical actions like hiding or hoarding items, it’s powerful enough to motivate a prospect to open an email.

Make sure you use real or implied scarcity in your nurture subject lines (where appropriate) to create urgency and increase open rates. This will improve most email marketing campaigns.

Continue the message of urgency in the content inside to get the most impact and drive prospects to convert.

Tip #3: Use power words in subject lines.

Certain words have the ability to capture attention and motivate people to action.

These words are often called “power words.”

As we previously explained,

Power words are words used by smart marketers and copywriters to trigger a psychological or emotional response.

Power words incite a feeling, action, or opinion. They make you desire a product, click ‘buy now’, or trigger a memory.

When space is limited – like in an email subject line – you have to make every word count. And power words (Ex. free, discount, now, sale, exclusive, guaranteed, elite, secret, and save) carry the most bang for the buck.

Make sure you prioritize dynamic, active, and precise words – think “boost” over “increase,” “multiply” over “grow,” and “reveal” over “tell” – in your subject lines.

As you review your subject lines, ask yourself if you’ve chosen the most powerful words to convey your message. Don’t be ashamed to keep a thesaurus handy – and use it because every single word counts.

Use power words whenever possible in all of your email marketing campaign subject lines.

Tip #4: Highlight value in subject lines.

“What’s in it for me?”

This is the fundamental lens through which most people assess a purchase. And you cannot afford to forget it.

If you fail to demonstrate (or promise) value, you’ve given people no reason to open your email. And they won’t.

Every good email subject line should either:

1. make it clear what’s in it for them or
2. suggest/imply that there’s something in it for them.

So, if you’re offering a free resource or service, lead with that in your subject line.

Or, if you want to share valuable information, write a subject line that lets the reader know that they will benefit from the content inside.

There’s not always room to lay out the full value your email contains. So, be strategic.

This is most important if you’re just starting a business and your business isn’t well known. You can’t rely on an established audience to open your emails because they don’t yet know your brand.

Remember that a bit of mystery helps to boost curiosity. And curiosity boosts your open rates.

Highlighting value should be a priority for every subject line. But, it’s most important early in a nurture campaign as you establish your credibility.

So, be sure to emphasize the value in your first few email subject lines. This will keep readers wanting to come back.

Tip #5: Include data in subject lines.

There’s no denying that data reigns supreme in marketing.

But, it’s also compelling for your average Joe and Jane.

People know that businesses are trying to sell them things. They also know that most of the emails they receive are trying to sell them things.

So, it should come as no surprise that providing some objective truth using concrete data will resonate with most audiences and improve email open rates.

In fact, as Tim Stoddart recently explained:

A study by CoSchedule of 155 million emails also showed that subject lines that included numbers experienced a 206% higher clickthrough rate than email subject lines without numbers.

So, if you’ve got data to support your email’s content, include pieces of that data in your subject line. This technique, while not necessary for every email, is effective throughout an entire nurture campaign.

Tip #6: Set proper expectations with subject lines.

An adequate subject line motivates a reader to open an email.

But, a truly successful subject line also sets proper expectations for what they’ll find inside.

Setting proper expectations delivers the following benefits:

• Filters customers based on actual interest in your content. Only the most qualified prospects will be motivated to open.
• This shows that your brand can be trusted to deliver on its promises.
• Increases satisfaction when readers see content in the email they were primed to expect.

Misleading subject lines may trick people into opening an email. But when people discover they’ve been misled, the disappointment, irritation, or anger they experience will undermine your efforts to build a loyal customer or client relationship. And it will hurt your brand.

In the long term, this will also negatively impact your email open rates.

It’s always worth double-checking your subject lines to ensure that you’re not accidentally sending the wrong message. Do this for every subject line in your nurture campaign.

For example, if the “from” email address is unusual or unknown, you might want to include your company name in the subject line to improve email open rates.

Tip #7: Keep subject lines short.

Email inboxes are personal spaces.

They’re microcosms of the people and things about which we care the most.

But, they’re also an overwhelming morass of sales and marketing messages simultaneously screaming for attention.

People’s inboxes have become exhausting, loud, distracting places.

And, long subject lines have no place there.

If you want to increase open rates for your marketing emails, make it easy on your reader.

Get to the point quickly.

A recent study from Backlinko has shown that email subject lines between 35 and 50 characters tend to perform best. That’s a great starting point to test for your audience.

Feel free to tweak your subject line length based on your audience’s responses. But, do avoid long, over-wrought subject lines.

People won’t read them.

And your emails will remain unopened.

Keep all of your nurture email subject lines as short as possible.

And don’t forget…

Best practices are a great place for you to start. But they’re only a starting point.

Testing your subject lines is a vital step in any nurture campaign. There’s an exception to every rule. And, there’s plenty of room to optimize for your audience.

So, don’t forget to test different subject lines and track your results.

The stronger your subject lines, the better your nurture campaigns will perform.