Want to increase your open rates, clicks, and conversions? One of the most effective tools at your disposal is A/B testing in email marketing. This method helps you understand what actually works with your audience—based on data, not guesswork.
In this full guide, you’ll learn what A/B testing is, why it’s essential in email marketing, what you should test, and how to run your own A/B tests effectively.
What Is A/B Testing in Email Marketing?
A/B testing, also known as split testing, is the process of sending two versions of an email to two small segments of your audience to determine which version performs better. The winning version—based on a predefined metric like open rate or click-through rate—is then sent to the rest of your list.
For example:
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Version A uses the subject line: “Save Big This Weekend!”
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Version B uses: “🔥 48-Hour Flash Sale Starts Now!”
The version with the higher open rate gets sent to the rest of your subscribers.
Why A/B Testing Matters
When done correctly, A/B testing in email marketing can help you:
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Improve open rates with better subject lines
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Boost click-through rates with better CTA wording or placement
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Reduce unsubscribe rates by refining email content
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Increase conversions and revenue by optimizing offers
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Make data-driven decisions for future campaigns
Rather than relying on instinct, you’ll learn exactly what resonates with your audience—and what doesn’t.
What Elements Can You A/B Test?
There are many components of an email you can test. Here are some of the most common and impactful:
1. Subject Line
Your subject line is the gatekeeper of your email. It determines whether or not your email gets opened.
What to test:
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Length (short vs. long)
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Use of emojis or punctuation
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Personalization (e.g., including first name)
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Tone (formal vs. playful)
2. Preview Text
The snippet that appears next to or under the subject line. This often gets overlooked but has a big impact on open rates.
What to test:
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Teasers vs. direct messages
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Calls to action
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Benefits vs. curiosity
3. Email Content
Once your email is opened, the content is what drives clicks and conversions.
What to test:
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Message tone
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Paragraph length
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Use of images or GIFs
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Storytelling vs. bullet points
4. CTA (Call to Action)
This is where conversions happen. Your CTA can make or break your email’s performance.
What to test:
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Button color or placement
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Text on the button (e.g., “Shop Now” vs. “Get Your Deal”)
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Number of CTAs in the email
5. Send Time or Day
Sometimes it’s not what you send, but when you send it. Timing can greatly affect your open and engagement rates.
What to test:
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Weekday vs. weekend
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Morning vs. afternoon
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Specific time zones
How to Run an A/B Test Step-by-Step
Here’s a simple process to follow when conducting A/B testing in email marketing:
Step 1: Choose a Single Variable to Test
Avoid testing multiple variables in one test. Focus on one element at a time—like the subject line or CTA. This ensures you know exactly what caused the performance difference.
Step 2: Define Your Goal
Decide what metric matters most. Do you want more opens? More clicks? More purchases?
Common goals include:
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Open rate (for subject lines and preview text)
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Click-through rate (for content and CTAs)
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Conversion rate (for sales, sign-ups, downloads)
Step 3: Split Your Audience
Choose a portion of your list—typically 10–20%—and split that group into two equal parts. Each half will receive one version of your email.
Example: If you have 10,000 subscribers, send Version A to 1,000 and Version B to 1,000.
Step 4: Send and Wait for Results
Let the test run for a set amount of time, usually 2–6 hours depending on the size of your list and your send times. Most email platforms will automatically track and determine the winner.
Step 5: Analyze the Results
Once the test period is over, review the results and declare a winner based on your goal. If your goal was more opens, see which subject line had the higher open rate.
Step 6: Send Winning Version to the Rest
After choosing the winning version, send it to the remaining 80–90% of your audience to maximize performance.
Best Practices for A/B Testing
To get the most out of your email testing efforts, follow these tips:
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Always test one variable at a time to keep results clear.
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Test consistently. The more you test, the better your campaigns will become over time.
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Use a large enough sample size. Too small and the results won’t be statistically significant.
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Test early in your campaign process. Don’t wait until the final send.
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Document your results to build a knowledge base of what works for your audience.
Tools to Run A/B Tests
Most modern email marketing platforms offer built-in A/B testing features. Some popular options include:
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Mailchimp
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ConvertKit
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ActiveCampaign
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MailerLite
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Klaviyo
These platforms allow you to easily set up tests, define goals, and analyze results without needing complex technical knowledge.
Final Thoughts
Whether you’re a solo entrepreneur or managing a large marketing team, mastering A/B testing in email marketing is a game-changer. It’s the difference between guessing and knowing, between poor engagement and high conversions.
To recap:
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Test one variable at a time
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Focus on goals like open rates or clicks
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Use a controlled sample size
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Analyze and apply what you learn
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Keep testing to stay ahead
A/B testing isn’t just for perfectionists—it’s for growth-minded marketers who want every email to perform better than the last. Start small, test often, and you’ll steadily unlock more success from every campaign.
Ready to improve your next email?
Choose one variable, run your first A/B test, and let the data guide your next big win.