How to write high-converting subject lines for your eCommerce emails

Email marketing remains one of the most powerful tools for driving sales, building customer loyalty, and creating brand awareness. However, crafting the perfect email is only half the battle. Getting your emails opened is the real challenge—and that’s where the subject line comes in.

Your subject line acts as the gatekeeper between your email and the customer. With inboxes cluttered by countless marketing emails, a well-written subject line can be the difference between an email being opened or deleted. To increase your open rates, you must write high-converting subject lines that grab attention and entice customers to click. Here’s how you can do it.

1. Keep It Short and Sweet

When writing subject lines, brevity is your best friend. Most people read their emails on mobile devices, where screen space is limited. A subject line that’s too long risks getting cut off, which reduces its effectiveness. To avoid this, aim for a subject line that is no longer than 50 characters. In fact, studies show that subject lines with fewer than 40 characters tend to perform better in terms of open rates.

Think about how you can convey your message as an Email Marketing Agency in as few words as possible. For example, instead of saying “Check Out Our Latest Collection of Winter Apparel for 20% Off,” you could say, “20% Off Winter Gear—Shop Now!”

2. Use a Clear Call to Action

Just like with any marketing copy, a clear and compelling call to action (CTA) is crucial in your subject line. A strong CTA prompts the recipient to take action and makes them curious about what’s inside. Phrases like “Shop Now,” “Don’t Miss Out,” or “Get Yours Before It’s Gone” are effective at creating urgency and a sense of importance.

However, the CTA should align with the content of your email. Misleading subject lines can frustrate recipients, leading to unsubscribes or spam complaints. If your subject line promises a sale, make sure the email follows through on that promise.

3. Incorporate Personalisation

Personalisation is one of the most effective ways to boost email open rates. In fact, emails with personalised subject lines are more likely to be opened compared to those without. People love seeing their name or other personal details in a subject line because it creates a sense of individual attention.

Adding the recipient’s first name to the subject line is a classic example, e.g., “Tom, Your Exclusive Offer Awaits!” But personalisation can go beyond just names. For example, you can reference past purchases, browsing behaviour, or even location: “Complete Your Look with These Shoes, Sarah” or “John, Get Ready for Winter with Local Favourites!”

4. Create Urgency or Scarcity

Creating a sense of urgency in your subject lines can drive immediate action. Time-sensitive words like “Hurry,” “Today Only,” or “Ends Tonight” prompt recipients to act quickly before the opportunity passes. Scarcity works in a similar way—phrases like “Limited Stock” or “Only 3 Left!” tap into the fear of missing out (FOMO) and can increase conversions.

However, be careful not to overuse this tactic. Constantly sending emails with urgent subject lines can desensitise your audience, making the technique less effective over time.

5. Utilise Numbers and Lists

Subject lines that include numbers or lists tend to grab attention and convey clarity. Numbers help to set expectations and make your subject line more specific. For example, “3 Must-Have Items for Your Summer Wardrobe” or “5 Ways to Save on Your Next Purchase” are clear and actionable, giving readers a reason to open the email.

Similarly, using percentages in discounts can also be effective. “Save 25% Today” or “50% Off on Selected Items” immediately tells the reader what’s in it for them.

6. Create Curiosity

Curiosity is a powerful motivator. A subject line that teases the content inside can spark curiosity and encourage the recipient to click through. This works particularly well for announcements or new product launches. Phrases like “You Won’t Believe What’s New” or “A Special Offer Just for You” make the recipient want to know more.

But be careful—don’t make your subject line too vague. The goal is to pique curiosity without being deceptive. Your email content should deliver on the promise made by the subject line.

7. Test and Optimise

One of the most important steps in writing high-converting subject lines is testing. What works for one eCommerce store might not work for another. A/B testing different subject lines can help you identify which ones perform best with your audience.

Test different elements of your subject line, such as length, tone, use of personalisation, or urgency. Track open rates, click-through rates, and conversion rates to see which subject lines resonate the most. Regular testing and optimisation are key to improving the effectiveness of your email campaigns over time.

8. Use Emojis Wisely

Emojis can add a playful or visually interesting element to your subject lines, helping them stand out in a crowded inbox. However, it’s essential to use them sparingly and in a way that complements your message. Overloading your subject line with emojis can make it seem unprofessional or spammy.

For example, a simple heart emoji might work well for a Valentine’s Day promotion: Show Some Love—Save 20% on All Gifts!” Make sure the emoji enhances the message rather than distracting from it.

Conclusion

A high-converting subject line is a blend of clarity, creativity, and relevance. It should grab attention, convey value, and motivate the recipient to take action. By keeping your subject lines short, personalised, and action-oriented, you can increase your email open rates and drive more conversions for your eCommerce store. Always remember to test and refine your approach to ensure your emails continue to engage your audience effectively.

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