#2: 8 Secret Ingredients for Irresistible Subject Lines That Boost Open Rates

The Power of Irresistible Subject Lines

When I first started with email marketing, I didn’t realize how much irresistible subject lines could impact results. I thought, “Why should I put too much effort into that little line when it’s only 5 or so words?”

So, my subject lines were pretty boring and generic. And honestly, my results showed it—my open rates were stuck around 10%.

Everything changed when I took a deep dive into email marketing. That’s when I learned about A/B testing and the power of irresistible subject lines. I realized that without a subject line compelling enough to get people to open the email, I was just wasting my time on the content.

I tested out different approaches, and the results were incredible. With just a few tweaks to make subject lines more engaging and attention-grabbing, I saw my open rates jump dramatically.

Listen on…

8 Characteristics of a Great Subject Line

Over the years, I’ve learned that there are 8 factors that can make or break an email’s open rate.

Here’s a breakdown of each one:

1. Is it clear?
   Clear subject lines tell the reader exactly what to expect without being overly complex or vague. Clarity builds trust and encourages opens.
   Example: “Your Complete Guide to Firmer Skin in 5 Simple Steps”
2. Does it spark curiosity?
   A little mystery goes a long way. Sparking curiosity can make readers wonder what’s inside, prompting them to click.
   Example: “This is hilariously accurate 🤣”
3. Does it create a sense of urgency?
   Time-sensitive offers can encourage people to act quickly to avoid missing out.
   Example: “Only 24 Hours Left Before It’s Discontinued Forever”
4. Does it speak directly to my ICA (Ideal Customer Avatar) or call them out?
   Using the recipient’s name or referencing their actions makes your emails feel more personal.
   Example: “Sarah, Here’s a Sneak Peek Just for You!”
5. Is it relevant to this group of people?
   A good subject line speaks to the needs or pain points of your specific audience. Avoid irrelevant messages, like promoting sundresses to those who’ve only purchased men’s clothing.
   Example: “Struggling to Find a Dress That Doesn’t Show Your Bum? I’ve Got What You Need.”
6. Does it sound like me and my brand?
   The tone of the subject line should match your brand’s voice, making your emails instantly recognizable.
   Example for a friendly brand: “You Won’t Want to Miss This!”
7. Is it the right length?
   Keep subject lines between 40-50 characters to ensure they’re fully visible, especially on mobile devices.
8. Does it encourage a specific action?
   Using action-oriented language makes the subject line feel more engaging and prompts the reader to take the next step.
   Example: “Revealed →→”

Common Mistakes to Avoid in Your Subject Lines

Crafting a great subject line takes practice, and it’s easy to make mistakes along the way. Here are some common pitfalls to avoid:

1. Using Generic Subject Lines
   Relying on Klaviyo’s default flow template subject lines is a no-go. These sound automated and don’t add personality or uniqueness to your emails. People can spot automated subject lines from a mile away!
2. Over-Explaining
   Subject lines that try to say too much end up looking cluttered and confusing. Keep it short and focused, and save the details for the email body.
3. Forgetting to Add a Subject Line
   This sounds simple, but it’s an easy mistake to make—and one that can send your email straight to the junk folder. Always double-check that your subject line is filled in.
4. Using Spam Trigger Words
   Certain words can trigger spam filters, especially for new accounts. Terms like “FREE,” “Congratulations,” “Act Now,” and “Click Here” are often flagged by email providers. Instead, focus on creating genuine interest without relying on salesy language.
5. Overusing Capitalization and Punctuation
   Using all caps or excessive exclamation points can come off as aggressive and is a common spam trigger. One exclamation point can add excitement, but more than that feels pushy.

Pro Tip: Avoid using these spam trigger words in subject lines, especially if your account is still new:

• Free
• Limited-time offer
• Congratulations
• Act now
• Click here
• Earn cash
• Discount

Learning to avoid these common pitfalls helps your emails stay out of the spam folder and improves open rates over time.

Proven Strategies and Formulas for Engaging Subject Lines

One of the best ways to come up with engaging subject lines is to look at examples that have worked on you! I actually created a folder in my Gmail called “Good Subject Lines.” Whenever I see an email subject line that grabs my attention and makes me want to click, I save it there. Then, when I’m writing emails, I can reference it for inspiration or adapt a subject line to fit my content.

Here are some go-to formulas and strategies I’ve found work well for e-commerce businesses:

1. Ask a Question
   Asking a question sparks curiosity and encourages readers to open to find the answer.
   • Example: “Looking for the Perfect Fall Sweater? 🍂”
2. Offer a Clear Benefit
   If readers know they’ll gain something valuable, they’re more likely to click.
   • Example: “Your New Favorite Jeans Are Just a Click Away”
3. Use Numbers or Lists
   Numbers are eye-catching and set clear expectations. They’re great for tips or guides.
   • Example: “3 Must-Have Accessories for Your Next Outfit”
4. Spark Curiosity
   Give just enough information to intrigue your readers without giving everything away.
   • Example: “Our Top-Selling Item Just Got an Upgrade!”
5. Personalization
   Including a name or tailoring the message to the reader can create a more personal connection.
   • Example: “Samantha, Your Wishlist Items Are Waiting!”
6. Create Urgency
   A time-sensitive offer or limited availability can motivate readers to act now.
   • Example: “Last Chance to Shop Our Summer Sale ☀️”
7. Make It Conversational
   Using a friendly, conversational tone makes the email feel less like marketing and more like a message from a friend.
   • Example: “Need a Style Refresh? We’ve Got You Covered”
8. Use Curiosity + Humor
   Humor can make subject lines stand out in the inbox and leave readers curious.
   • Example: “Ready to Fall in Love with Your Closet All Over Again?”

By incorporating these formulas, I’ve found my open rates consistently improve. It’s all about finding the right balance and matching the tone to my audience.

Examples and Testing Tips for High-Performing Subject Lines

One of the most effective ways to improve your subject lines is to test them out and see what resonates with your audience. I’ve tested many subject lines over the years, and some of my highest open rates come from specific approaches like personalization, curiosity, and benefit-driven language.

Here are a few of my best-performing subject lines and their open rates:

• “Recommended for you {{ first_name|title|default:” }}” – 82.25%
• “This is your last chance to get a free sign!⌛” – 76.25%
• “Can you guess our best-selling sign?” – 84%
• “Sips & snacks of summer…🍉” – 84.46%
• “Hi {{ first_name|title|default:’there’ }}, this is us ➤➤” – 72.21%
• “The secret to a welcoming entry…>” – 72.08%
• “Did you know we can create a free front porch mock-up for you?” – 88.9%

With a list of around 4,500 people, these open rates are far above the industry average of 21%. Testing has shown me which styles and strategies my audience connects with most, and the results speak for themselves!

The Power of A/B Testing

A/B testing is essential to refining subject lines. Here’s what I discovered through testing:

• Personalization Wins: Subject lines that include a first name or reference something unique about the reader, like “Recommended for you {{ first_name }},” tend to perform exceptionally well.
• Curiosity Boosts Engagement: When I use questions or statements that spark curiosity (e.g., “Can you guess our best-selling sign?”), I often see a spike in open rates. People want to know the answer!
• Clear Calls to Action: Phrases like “Last chance to get a free sign!” create a sense of urgency and guide readers to take action immediately.

A/B testing takes the guesswork out of subject lines by giving you hard data on what drives opens for your specific audience. It’s a tool I’d recommend for any e-commerce business looking to maximize their email performance.

Your subject line is the gateway to your email’s success. By focusing on clarity, curiosity, relevance, and personalization, you can create subject lines that truly resonate with your audience and drive higher open rates. A little effort in crafting these small but mighty lines goes a long way in connecting with your readers.

Ready to start crafting winning subject lines of your own? I’ve put together a free guide with 50 irresistible subject lines to help you get started. These examples are designed specifically for e-commerce businesses, giving you an instant boost in inspiration and effectiveness.

👉 [Download your free 50 subject lines here!]

Experiment with A/B testing, try out the different formulas we discussed, and let your emails shine in your customers’ inboxes. Happy writing, and here’s to higher open rates!

Liezle 🦓