Email marketing is still one of the most effective digital marketing tools, but sending the same message to everyone will only take you so far. To improve engagement and results, you need to test, adjust and optimise.
A/B testing, also called split testing, makes this possible. By sending different versions of an email to a portion of your audience, you can see which performs better and then use the winning version for the rest.
What is A/B testing?
A/B testing compares two or more versions of an email to find out which one achieves the best outcome. Subscribers are divided into groups, each receiving a different version of the email. Once you have measured the performance, the version with the best results is sent to the remainder of your audience. This approach replaces guesswork with reliable, data-driven insights.
What to test in your email campaigns
You don’t need to change an entire email to learn something useful! Start with one element at a time so you know what influenced the results. Some of the most common areas to test include:
- Subject lines: short versus long, with or without emojis, or a question versus a statement.
- Sender name: use a personal name or keep it brand-focused.
- Preview text: short and punchy or longer and more descriptive.
- Calls to action: try different wording, colours, placement or button styles.
- Content layout: text-focused versus image-heavy, or plain text versus HTML design.
Why these tests make a difference
Testing helps you make better decisions based on evidence rather than assumptions. Even small changes, such as adjusting the subject line, can increase open rates.
Experimenting with layouts or calls to action may reveal surprising patterns in how people engage with your emails. By forming a clear hypothesis, for example whether urgency in a subject line improves engagement, you can build a strategy that delivers consistent results.
Best practices for successful A/B testing
- Test only one element at a time so you can be confident about what caused the difference.
- Make sure your test groups are large enough to give meaningful results.
- Define a clear objective such as increasing opens, clicks or conversions.
- Run tests more than once to confirm that results are consistent and not just due to novelty.
- Keep a record of your tests and outcomes so you build a library of insights for future campaigns.
- Share your findings with your wider team so the learnings can improve other areas such as social media and website content.
Final thoughts
A/B testing in email marketing is one of the simplest ways to improve performance. By making small changes, testing carefully and learning from the results, you can create campaigns that resonate with your audience and deliver better returns. Start with subject lines or calls to action, then gradually test other elements to keep improving over time.
