Eira Wexford
You ever send an email to your whole customer list and just… hope? You cross your fingers, maybe say a little prayer to the marketing gods, and wait. It feels like throwing spaghetti at a wall to see what sticks, right? For a small business, every single email counts. You can’t afford to just guess.
This is where the idea of A/B testing comes in. It sounds super technical and scary, but it’s not. It’s really just a simple idea. It is the practice of comparing two versions of the same thing to figure out which one does better. That’s it.
By 2025, inboxes are going to be even crazier places. More noise, more competition. Your little email has to fight hard to get noticed. Guessing isn’t going to cut it anymore. So let’s talk about how to stop guessing and start knowing what actually works for your people.
What Even Is A/B Testing in Email? (And Why You Should Care)
So, A/B testing. It’s also called split testing. It’s a pretty straightforward method, really.
You take your email list. You split it into two random groups. Group A gets one version of your email. We’ll call it Version A.
Group B gets a slightly different version, Version B. The change could be tiny. A different subject line. A different picture.
Then you watch the numbers. Did more people in Group A open the email? Did more people in Group B click the link?
Whichever version gets the better result is the winner. Now you know something real about your audience, not just a hunch.
For a small business, this is huge. You don’t have a giant budget to waste on campaigns that don’t work.
Every little improvement in your open rate or click rate adds up. It means more traffic, more leads, and hopefully, more sales. All from just changing one little thing.
Think of it like this. You bake a chocolate cake. Then you bake another one, but this time you add a little coffee to the batter.
You have your family try both without telling them the difference. If they all like the coffee one better, you know what to do next time you bake a cake. That’s A/B testing.
Getting Started: The A/B Testing Stuff You Can Actually Do
The cool thing is you don’t need some wild software to do this. Most email marketing platforms, like Mailchimp or ConvertKit or whatever, have this stuff built right in now. It’s usually just a button you click. The hard part is deciding what to test.
The Easy Wins: Testing Your Subject Lines
Your subject line is basically the bouncer at the door of your email. If it’s boring or weird, nobody’s getting in.
It is often considered to be the first and most important thing you should probably test.
The goal here is simple. Get more people to open the email. A higher open rate means more eyeballs on your message.
Here are some things to try:
Question vs. Statement: “Got your summer plans yet?” vs. “Our new summer collection is here.”
Using an Emoji vs. No Emoji: “☀️ Our summer sale is on!” vs. “Our summer sale is on!”
Personalization: “Sarah, a special offer for you” vs. “A special offer for you.”
Length: A really short subject line vs. a longer, more descriptive one.
Just pick one idea and try it. The results might honestly surprise you.
Beyond the Open: What to Test Inside Your Email
Okay so they opened the email. Great. Now what? The inside of the email is where the action happens.
You want them to click something, right? Buy something? Read something? Here are some tests to run.
Your Call to Action (CTA): This is the button you want people to click. Test the words on it. “Shop Now” versus “See the Collection.” You can also test the button color. A bright orange button might get more clicks than a gray one. You never know.
Images: People respond to pictures. Try an email with a clean product photo against a plain background. And then test it against an email with a “lifestyle” photo, with a person using your product. Which one makes people want it more?
The Actual Words: This is your email copy. You could test a version that’s super short and to the point. The other version could tell more of a story about the product. Some audiences want facts, some want feelings.
Who it’s “From”: The sender name matters. You could test your standard “The Awesome Widget Co.” against a more personal “Dave from The Awesome Widget Co.” A person’s name normally feels a bit more human.
The Nitty-Gritty: How to Run a Test
So you have your idea. Let’s say you want to test your subject line. How do you do it for real?
First, you pick only one thing to change. If you change the subject line AND the main image, you won’t know which change caused the result. One thing. That’s the rule.
Next, you split up your list. Your email tool will do this for you. It’ll send Version A to a small part of your list, maybe 10%, and Version B to another 10%.
Then, you wait. You have to decide what “winning” means. For a subject line, it’s the open rate. For a CTA button, it’s the click rate.
The email tool watches the results for a few hours. It sees which version is winning. Then, it automatically sends the winning version to the rest of your list. It’s kind of like a mini-election.
Common Mess-Ups People Make with A/B Testing
This all sounds pretty good, but people mess it up sometimes. It’s easy to do.
A big mistake is testing too many things at once. It’s tempting, but as I said, you won’t learn anything useful. You’ll just have confusing numbers.
Another one is not having a big enough group. If you only send each version to 20 people, the results are just luck. You need a decent sample size for the numbers to mean anything.
And please, don’t end the test too early. Some people open emails right away, others wait a day. Give it at least 4-6 hours, maybe even 24 hours if your audience is slower, to get a real picture.
The biggest mistake? Not using what you learned. If you find that emojis in subject lines get you more opens, start using emojis in your subject lines! The whole point is to make your next email better.
Looking Ahead to 2025: A/B Testing Gets a Little Weird
As we move into 2025, A/B testing is getting a little smarter. It’s not just about you manually thinking of two subject lines anymore.
Artificial intelligence is already writing email copy. You could soon just tell an AI “give me five different subject lines for this email” and it’ll spit them out. Then you can test them against each other. It takes some of the work off your plate.
We’re also seeing more complex tests. Instead of just A and B, you might test A, B, C, and D all at once. This is called multivariate testing, which is a whole other can of worms but it’s becoming more accessible.
And personalization is getting crazy. You might test sending an email with a picture of a red shirt to people who have bought red things before, and a blue shirt to people who like blue things. The emails will build themselves based on data. But the core idea is still the same, you’re testing one thing against another to see what works better.
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FAQs About A/B Testing Emails
1. How big does my email list need to be to start A/B testing?
There’s no magic number. But you want enough people in your test groups for the results to be reliable. Generally, if you can send each version to at least a few hundred people, you’re in a good spot. If your list is smaller, you can still test, just know the results are less certain.
2. How long should I let a test run before deciding on a winner?
This depends on your audience. A good starting point is 4 hours. That usually catches the majority of openers. For some businesses, waiting 24 hours might be better. Look at your own email reports to see when most people typically open your emails.
3. What’s the single best thing to test first?
The subject line. It’s easy, and it has a big effect on your open rate. If people don’t open the email, nothing else you test inside it matters. Start there.
4. What’s the difference between A/B testing and multivariate testing?
A/B testing is simple: you test one change between two versions (Version A vs. Version B). Multivariate testing is more complicated. you test multiple changes at once in many combinations (e.g., two subject lines and two different images, creating four versions) to see which combination performs best. Stick with A/B testing to start.
5. Do I need special software for this?
Probably not! Nearly all modern email marketing providers (like Mailchimp, Klaviyo, ConvertKit, etc.) have A/B testing functionality built into their standard plans. You just have to look for the “create A/B test” or “split test” option when you set up your campaign.
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Key Takeaways
A/B testing is just trying two versions of an email to see which performs better. It’s not as complex as it sounds.
For small businesses, it’s a way to stop guessing and start making choices based on what your customers actually do.
Start by testing your subject line. It’s a simple test that can have a big impact on your open rates.
Only test one single thing at a time. Otherwise, you won’t know what caused the change in performance.
Use what you learn from your tests to make your future emails better. That’s the whole point.
