Subject Line Testing in Email Marketing: What We Learned From December A/B Tests in Klaviyo

When was the last time an emoji caught your attention? Whether it’s a smiley, a coffee cup, or a snowflake, emojis have become a staple of digital communication—and, as it turns out, a powerful tool in email marketing.

At Dispatch, we recently conducted A/B tests for an 8-figure e-commerce partner to understand the impact of emojis in subject lines (SL) and preview text (PT). The results? Consistently, emails with emojis outperformed those without.

Here’s what we learned and how you can use this insight to optimize your own campaigns.

The December Test: Do Emojis Really Work?

In December, we tested multiple campaigns featuring variations in their subject lines and preview text—one version with emojis and one without. Across several campaigns, emails with emojis showed a slight but reliable lift in open rates.

Here’s a quick breakdown of one test:

• With Emoji

  • Open Rate: 81.77%

  • Click Rate: 1.17%

  • Revenue per Recipient: $45

• Without Emoji

  • Open Rate: 81.11%

  • Click Rate: 1.36%

  • Revenue per Recipient: $92

    
    

While the emoji version didn’t lead to the highest revenue per recipient in this specific case, the lift in open rates was clear. This trend held steady across other campaigns, highlighting how emojis grab attention in crowded inboxes. It’s worth noting that the boost was incremental rather than dramatic, but in email marketing, even a slight increase in open rates can compound into significant returns.

Why Emojis Work (But Not Always)

The slight lift in open rates isn’t just about aesthetics; it’s about psychology. Emojis:

1. Catch the Eye: In a sea of text, a small visual cue can make your email stand out.

2. Add Personality: Emojis humanize your brand and convey emotion or urgency in a way words sometimes can’t.

3. Set the Tone: The right emoji can reinforce the theme of your campaign, like 🎁 for a holiday sale or ☕ for a coffee brand.

   
   

That said, what works for one audience may not work for another. In one of our campaigns for AeroPress, emojis added to subject lines didn’t result in a significant lift in performance. This underscores the importance of testing, because every audience is unique.

How to Test Emojis in Your Campaigns

If you’re new to using emojis in email marketing, start with a simple A/B test:

1. Pick One Campaign: Select a campaign with a large enough audience for statistical significance.

2. Choose One Relevant Emoji: Think about your audience and the theme of your campaign. For example:

   • A coffee ☕ for a morning routine email.

   • A star ⭐ for highlighting a sale.

3. Monitor Metrics: Track open rates, click rates, and conversions for both variations.

4. Iterate: Use your findings to refine your strategy for future campaigns.

   
   

Pro tip: Don’t overdo it. Emojis should enhance, not clutter, your messaging. A single, relevant emoji often works best.

Key Takeaways for Brands

The data is clear: emojis can help, but they aren’t a one-size-fits-all solution. Their effectiveness depends on your audience, your messaging, and even the time of year.

Here’s what you can do today to optimize your email marketing:

• Test emojis in subject lines and preview text to see how your audience responds.

• Use emojis sparingly and make sure they align with your brand’s tone.

• Combine emoji testing with other strategies, like segmentation and personalization, to maximize engagement.

  
  

If you’re unsure where to start or want to dive deeper into optimizing your email and SMS marketing channels, Dispatch is here to help.