A/B Testing in Email Marketing: How to Improve Open and Click Rates

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You stare at your email analytics, frustrated. Your open rates are stuck. Your click-through rates are low. You’re putting in the work, but you’re just guessing what your audience wants to hear. Is it the subject line? The time you send? The offer itself?

This guessing game is exhausting. But what if you could stop guessing and start knowing?

What if you had a simple method to ask your audience, "Which of these do you prefer?" and have them tell you with their clicks?

This isn't a fantasy. It's the power of A/B testing.

A/B testing is like having a friendly conversation with your audience.

You present two options (A and B) and let their behavior tell you which one they like better. It’s the secret weapon that takes the mystery out of email marketing and replaces it with data-driven confidence.

Let’s explore how this simple process can transform your email results from mediocre to magnificent.

What is A/B Testing? (It’s Simpler Than You Think)

A/B testing, sometimes called split testing, is a simple experiment. You create two versions of one email and send them to a small portion of your list to see which one performs better.

• Version A is your control (what you would normally send).

• Version B is your variation (with one single thing changed).

You test these two versions on a small segment of your audience. The winning version is then automatically sent to the rest of your list.

Think of it like tasting two different recipes for soup. You make a small batch of each (the test). You have a few friends taste both (your test audience).

They all prefer Recipe B (the winner). So, you make a huge pot of Recipe B for the whole party (your main list).

You’re not wasting the big pot on an untested recipe. You’re making a data-backed decision that pleases the most people.

Why Bother? The Real Benefits of A/B Testing

You might think your intuition is a good guide. Sometimes it is! But our intuition is often biased. What we think will work isn't always what actually works with our specific audience.

A/B testing removes the bias and gives you cold, hard facts.

The benefits are huge:

• Higher Open Rates: Discover the subject lines that make people click.

• More Clicks: Find the call-to-action buttons and language that drive action.

• Increased Sales: Small improvements in open and click rates can lead to a significant boost in revenue over time.

• You Learn About Your Audience: Every test teaches you something new about what your subscribers want and value.

• It Builds Confidence: When you know what works, you can send emails with certainty, not hope.

According to Campaign Monitor, brands that A/B test their emails see an average return of $38 for every $1 spent. It’s one of the highest-ROI activities in marketing.

What You Can (and Should) Test

You can test almost anything in an email, but it’s best to start with the elements that have the biggest impact. Test one thing at a time.

If you change the subject line, the sender name, and the content all at once, you won’t know which change caused the result.

Here are the best places to start.

1. Subject Lines (The King of Opens)

Your subject line is the gatekeeper. It’s the number one factor determining whether your email gets opened. Even a tiny improvement can have a massive impact.

What to test:

• Length: A short, punchy subject line vs. a longer, more descriptive one.

• Tone: A question vs. a statement. ("Struggling to focus?" vs. "3 ways to improve your focus")

• Personalization: Using the subscriber’s first name vs. not. ("Sarah, a tip for you" vs. "A tip for you")

• Emojis: Using an emoji vs. using no emoji. ("Your guide is inside 🎁" vs. "Your guide is inside")

Example Test:

• Version A: "Our Summer Sale Starts Now!"

• Version B: "☀️ Don't miss these summer deals inside!"

2. Sender Name (The Trust Signal)

The "from" name is the second thing people see. A small change here can dramatically affect whether someone trusts your email enough to open it.

What to test:

• Your Name vs. Your Business Name: "Jane Doe" vs. "Jane's Business Co."

• Personal + Business: "Jane at Jane's Business Co."

Many people prefer receiving emails from a person rather than a faceless company. Testing this can be a game-changer for trust and recognition.

3. Preheader Text (The Supporting Actor)

The preheader is the short snippet of text that appears next to or below the subject line in most email inboxes. It’s prime real estate that often gets overlooked.

What to test:

• Repeating the subject line vs. adding new information.

• A call-to-action vs. a summary of the email.

Example:

• Subject: Your weekly planning tips are here

• Preheader A: Inside: your free planner template.

• Preheader B: Read now to save 5 hours this week.

4. Call-to-Action (CTA) Buttons (The Conversion Engine)

Your CTA is where the magic happens. A poorly designed or worded CTA can kill your conversion rate, even if your email is brilliant.

What to test:

• Button Text: "Learn More" vs. "Get Your Free Guide" vs. "Yes, I Want This!"

• Button Color: A bright color that contrasts with your email vs. a more subtle color.

• Button Placement: At the end of the email vs. in the middle of the content.

Pro Tip: Action-oriented, benefit-driven text almost always outperforms generic text like "Click Here."

5. Send Day and Time

The best time to send an email is when your audience is most likely to see and open it. This can vary wildly depending on your niche and audience.

What to test:

• Morning vs. Evening: Tuesday at 10 AM vs. Tuesday at 7 PM.

• Weekday vs. Weekend: Wednesday vs. Sunday.

Most email platforms, like Mailchimp, have built-in tools to test send time automatically.

How to Run an A/B Test: A Step-by-Step Guide

Running a test is straightforward. Here’s how to do it right.

Step 1: Form Your Hypothesis

Start with a clear idea. "I believe that [Version B] will get a higher open rate because [reason]."

• Example: "I believe that using an emoji in the subject line (Version B) will get a higher open rate because it will stand out in a crowded inbox."

Step 2: Create Your Two Variations

In your email platform, create your email as usual. Then, find the A/B test option. You will be prompted to create a second version (B) where you change only one element.

Step 3: Choose Your Audience and Split

Most platforms will automatically split your test audience for you. A good starting point is a 50/50 split to a combined total of 20-30% of your list. So, if you have 1,000 subscribers, you might send Version A to 150 people and Version B to 150 people.

Step 4: Decide What “Winning” Means (and for How Long)

You need to choose your winning metric before you send.

• For a subject line test, the winner is usually the one with the highest open rate.

• For a CTA test, the winner is the one with the highest click-through rate.

Also, set a time limit for the test—usually 4 to 24 hours is sufficient. This ensures the results aren't skewed by people who open emails days later.

Step 5: Analyze the Results and Send the Winner

When the test is over, your email platform will declare a winner. It will then automatically send the winning version to the remaining 70-80% of your list. You now have data to inform your future emails!

A Real-World A/B Test Example

Let's imagine you are a business coach promoting a free webinar.

• Your Goal: Get the highest registration rate for your webinar.

• Your Hypothesis: "A subject line that focuses on the result (more clients) will get more opens than one that focuses on the topic (webinar)."

• The Test:

  • Version A (Control): "You're invited to my webinar on lead generation"

  • Version B (Variation): "The secret to booking 3 new clients this month"

• The Result: After 4 hours, Version B has a 35% open rate, while Version A has a 22% open rate. Version B is the clear winner and is sent to the rest of the list.

This one test just gave you a valuable lesson: your audience responds better to benefit-driven language than to feature-driven language.

Common A/B Testing Mistakes to Avoid

• Testing Too Many Things at Once: This is the biggest mistake. If you change the subject line, the images, and the CTA, you’ll have no idea which change drove the result.

• Ending the Test Too Soon: Don’t check results after 30 minutes and declare a winner. Let the test run for a statistically significant amount of time.

• Testing on Too Small of a Sample: If you only send your test to 10 people, the results won't be reliable. Use a large enough segment to be meaningful.

• Ignoring a “Loser”: There are no failed tests, only learning opportunities. If Version B loses, you’ve still learned something valuable about what your audience doesn’t like.

Your First A/B Test: A Simple Plan

You don’t need to become a data scientist. Start small.

1. Pick your next email send. It could be your weekly newsletter.

2. Choose ONE thing to test. Start with your subject line—it’s the easiest and has the biggest impact.

3. Create two different versions. Use the formulas we discussed.

4. Use your email platform’s A/B testing tool to set it up. It will guide you through the process.

5. Record what you learn. Keep a simple spreadsheet of your tests and results.

A/B testing turns email marketing from a guessing game into a conversation. You’re no longer shouting into the void; you’re asking questions and listening to the answers. Start with one test.

The data you collect will be the foundation for an email list that eagerly awaits your next message.