A/B Testing in Email Marketing & Best Split Test Practices 

Jun 29, 2021 - By Camilla Mackeviciute

Turn strategy into action
Don’t leave your perfect strategy untapped. Unlock its potential with Sender and see your sales explode.
Get Started For Free

Having an email marketing strategy is a great way to build your brand, but it can also be difficult to know where to start. 

There are so many different factors that go into creating an effective campaign.

A/B testing in email marketing is one of the best ways for marketers and business owners alike to make sure they’re getting everything right with their campaigns. 

By using this strategy, you’ll be able to test different elements of your emails (like subject lines or even images) or even see which email performs better on different occasions so you can keep what works and adjust what doesn’t. 

This will allow you to create more effective email campaigns that resonate with your audience.

Using the Split testing method is one of the most effective ways of testing your email campaigns. The technique involves testing the original email campaign copy against another version, which consists; of changing the call to action, the email subject line, or the design.

The rule here is that you must only change one element to develop another version. Once you have these two versions of the same email, you can send them out and find the variant that performs better.

It appears simple, but like any experiment, there are specific rules to follow to ensure that your testing is valid and bears good results.

Here are some best practices to follow when conducting a split test:

Change One element At A Time – It’s always important to keep in mind that split testing requires you to test one element at a time. Therefore, if you change more than one element at a time, it will no longer be regarded as split testing.

Use A Valid Hypothesis – Implementing tasks without having a firm foundation will lead to failure. To succeed, you need to begin with the correct hypothesis, the foundation. Your thesis should cover observation of what’s currently happening, what could be the possible reason, how to improve the situation, and how to determine if your solution has been effective.

Prioritize Your Test – When running a split test, it is essential, to begin with, your most frequently used and necessary sent emails.

Use Statistically Significant Emails – It is advisable to test with big numbers to rely on the results effortlessly. It is necessary because a more extensive testing sample will yield better statistically significant results.

Compare Same Conditions – Comparing split testing results from different conditions might lead you astray. For example, do not compare the open rates of emails sent over the holidays with those sent on a working weekday. So, it is better to split test emails sent within the same conditions.

Record the Results – It is advisable not to ignore the results from the tests because this will defeat the purpose. Instead, record the data and pay attention to the findings because this will help you make more impact with your emails.

What is A/B Testing in Email Marketing?

Let’s start off with the general definition.

A/B testing is a marketing technique that splits traffic into two different versions and compares the conversion rates. One version will have changes made to it, while the other will be the original. 

Understanding the numbers is a key step of every successful business endeavor – no matter at which stage it is – and this is nothing different. In fact, knowing your numbers is what ultimately leads to financial freedom in your business.

The idea with knowing your numbers in an email marketing A/B test, is that if one performs better than another, you know what changes are worth making. 

When it comes to email marketing, A/B testing helps determine which email performs better than others by sending emails with varying messages to your customers – this is a technique that all email marketing experts use to get more out of each email that they send.

The only two things that change in an email A/B test are the subject line and the email content

When you send an A/B test campaign, make sure to keep a close eye on your open rate and click-through rate so you can understand how people respond to different versions of your offers. This is important because these metrics help determine which version performs best for future campaigns.

When it comes down to it, it’s all about data: when you use this technique correctly, you’re able to collect information from customer feedback that would have taken months or years to determine otherwise, and you’ll end up with a more refined customer profile.


This refined customer profile can then be segmented and the right people are sent various offers that are more in-line with what these people are interested in.

Also read: Email List Segmentation: The Definitive Guide

Benefits of A/B Testing

Increasing Profits: The purpose of split testing emails is to enable your brand to increase its conversion rate. A better conversion rate means more profit for your business. Also, A/B testing allows your business to get to a larger audience suitable for the company.

Reduced Bounced Rates: No brand is happy when visitors who their website bounce off very fast without spending time on the website. With A/B testing, you can discover a winning combination of variables to make people engage better with your website.

Helps Identify Issues: Your marketing campaign can fail due to a few unnoticeable errors. With A/B testing tools, you can discover and fix these little errors, making your campaign run smoothly.

It Is Multi-functional: A/B testing doesn’t limit to just online images, forms, and actual texts; it applies to any online and offline advertising and marketing campaigns. It isn’t easy to know what potential clients or website visitors want. Still, a little tweak in your advertising and marketing campaign can significantly lead to more engagement and conversion rates.

Relevant For Low Data Rate Testing: Although it is advisable to use actual data when split testing, it is not compulsory. If you are a new business and do not have a lot of data to test with, you can still observe and determine which version of ads your visitors engage with the most.

Reduce Cart Abandonment: Cart abandonment is one of the challenges Ecommerce brands face, and there are many reasons for this phenomenon. But with a process like A/B testing, you can tweak things like colors, check-out page text, and where the shipping cost is displayed can help your brand reduce cart abandonment.

Improving Content: Content is still one of the most fundamental things in any advertising or marketing campaign. A/B testing is a reliable way to provide data analysis that will help you improve the content for marketing and advertising your brand.

How Does A/B Testing Actually Work?

The first step to A/B testing is setting up your email content – that means writing two different versions of the same message (or offer) side-by-side and then sending them out at the same time.

When it comes down to it, there’s no right way when it comes to creating an A/B test campaign; as long as both messages are communicating the key points in different ways, you’re on track. 

What happens next? 

Once people have responded by opening the email or clicking on a link, you can check which one they engaged with more. 

For example: if you have an opt-in offer for your eBook and people opened the “A” version of the message more, that means it performed better than the “B.”

How to Outclass in Email Subject Line Testing

Whenever you think of subject lines, you need to ask yourself, “what is the first thing I want a customer to see about my brand or business email?”

A/B Testing is your brand’s ticket to more clicks, more email opens, and higher conversion rates. It means that if you take the A/B test, you have to be good at it, and it should be adequate. To capture and woo your audience, you must develop catchy and strong email subject lines.


List Segmentation

It’s not advisable to send an email to your entire list without first testing it with a smaller group. Everyone on your email list can’t resonate with one specific type of subject line. So, by dividing your list into segments, you can target a particular kind of people with different features.

Each segment will possess characteristics and traits that will enable you to study better and understand your targets. First, you must decide what specific aspect of your campaign resonates better with a particular segment.

Send Emails To A Portion in Your Emailing List

It benefits those with large email lists; you can test different lines with little segment groups. It is a good move because you will be trying your emails with only a tiny portion of your entire list.

Once you have tested all the lines and decided which one is the best (like which one has a better open rate), you can send the emails with the best subject lines to the more significant portion of your email list.

Testing your email subject line with a smaller portion of your list makes you avoid the mistake of sending out the weakest email subject line to your whole list. It might not work for those with a small email list because you might not get the accurate results for testing out only a couple of contacts.

Know Your Online Target Audience

It is necessary to know where your target audience hangs out online. It will make it easier for you to understand what interests they have, their behavior, and buying habits. In addition, you will create creative and killer marketing campaign copies once you have a better understanding of how your target audience behaves.

You can know your audience by using different channels like researching industry-relevant forms, gathering buyer data, social media platforms, and customer surveys. To be ahead of others, you must diligently carry out audience research.

Recycling Successful Marketing Copies

It would help if you did not mistake abandoning copies that have proven successful in the past. Instead, recycling such content into your email campaign and analyzing its engagement with clients is advisable.

In determining the appeal of these email copies, it is good to run them through email testing software. This step will help you know its appeal and gain better email marketing insights and cues for a better call to action and keywords.

Subject Line Spam Check & Analyzer

With all the noise in our inboxes nowadays, it’s hard to make your email stand out.

If you’re looking for a way to grab your readers’ attention, don’t email clients without using a subject line spam-checker first.

Using a free subject line tester can boost your email open rates and show your subscribers that you care about their email experience.

You’ll also be able to tell if anything in the subject line wording has to be changed.

Here are some of the best free subject line tester tools to consider:

I highly suggest that you check these out and, more importantly, use them before sending your following email to ensure that your subject line (or lines if you’re A/B testing) are up to the required standard.

The harsh truth is that subject lines play a big part in whether your marketing emails will be opened or not. So, if you have put in the serious work of coming up with a marketing copy, you still need to submit that copy through an analysis process.

Analyzing your subject line and the body of the email will reveal how effective the subject line is. You need to use a subject line tester that will make your emails clickable, thereby increasing the open rate for your emails.

Many analyzing tools can prevent your emails from landing in clients’ spam folders on your email list. These analyzing tools include:

  • Test Subject by Zurb: This tool is best for creating mobile-friendly email subject lines.
  • Spam Check By Postmark: It is best for measuring the spam score for outgoing and incoming emails.
  • Send Check It: Has sixteen criteria that enable you to score the quality of email copy.
  • Touchstone: This tool enables you to compare your subject line with an extensive database of 21 billion emails.
  • ISnotSpam: This tool enables you to beat spam filters.
  • Subject Line Tester from Moosend: This is a more sophisticated tool because it uses AI technology to rate your subject line’s quality, comparing it to the industry’s benchmark.

These analyzer tools will help you increase the open rates for your emails, and it is left for you to pick the one that best suits your needs.

Ideal Subject Line Length

The subject line of your email is the first experience people have with you. If it’s too long, they’ll never get to see what your email is all about. 

The first step in crafting an email is to optimize your subject line. This way, most people can receive emails on their iPhones or Gmail and be able to understand what the email is about. The iPhone limits a subject line to 36-41 characters while Google’s limit for Gmail goes up to 70 characters.

If you can’t fit all of your message in that range, try using a preview text to entice the reader into clicking on, and opening your email. 

This means that with the right subject line, people will become interested enough in what you’re saying as well as curious enough to open the email to get to the main content.

A/B Testing Email Lists

It’s become more and more important to maintain an engaged email list. With the increased amount of emails that people get, it’s now a lot easier for businesses to lose potential customers because they’re not engaging with their messages. 

A/B Testing allows you to test different versions of your email to see which one has the best open rate, click-through rate, or unsubscribe rate. 

The results will show you what type of content works best and who your most engaged readers are, so that you can increase engagement even further.

It’s really important to know about your email list, and the types of emails you’re sending.

This ensures that you’ll be able to tell in advance if your messages are likely to go straight into the spam folder or be delivered to the inbox as expected.

A/B Testing Email Campaigns

Are you still testing one email campaign at a time? If so, then it’s time to switch to multivariate testing. A multivariate test in email marketing is the process of sending different variations of an email to your list and analyzing which one performs best based on open rates, click-through rates, and conversion rates. 

This means that you’ll be able to significantly increase the number of emails you can send and still maintain a high open-rate. 

Multivariate testing is not only an excellent way to test email content, but also provides insights into your list’s preferences and behaviors. 

When you do this, you will learn what your email subscribers like and don’t like by analyzing their responses. 

This knowledge will help shape future campaigns so that they resonate with recipients better – leading to higher click-through rates, conversion rates, or both.

Email A/B Testing Best Practices

There are many different best practices for A/B testing, with some that may work better than others depending on how your audience responds.

Here are some tips for successful email marketing A/B tests:

Create two versions of an email campaign

If you’re sending out an offer, come up with an email marketing test plan to try out different prices (e.g., $9 or $10) to see what works best.

You’ll be surprised at the results. What’s fun about these experiments is that they can give us insight into why people are making certain decisions.

Also read: PRO Email Marketing Calendar Template + Tips

Consider testing the different variables of an email

A/B tests can grade all sorts of things to see what will work best with your audience, including:

  • Subject lines;
  • Image placement;
  • Offer wording.

Track conversion data

Track conversion data using a tool like Google Analytics by creating goals and events that measure user behavior after clicking on an email campaign.This can help you determine how successful specific campaigns have been in relation to others.   

Knowing this information is crucial for determining which types of messages are resonating with readers and should be pursued more heavily in future emails. It’s also important for knowing when it’s time to stop doing something if it isn’t working.

AB Testing Statistics

FORTUNATELY, with A/B Testing, you can say goodbye to the stress you face when you need to pick from two options. Most times, we result in flipping a coin when we are not particularly sure, which can have repercussions on the outcome.

But with A/B Testing, you will be making informed choices based on statistics and user performance. Statistical analysis is a better way of predicting the outcome of events rather than guesswork. With proper statistical analysis, you can use the information to predict a result you do not know with reasonable accuracy.

So, to use A/B Testing correctly and be ahead of your competitors, you need good statistical know-how. It is essential because, with statistics, you can interpret results that help you make better business decisions. But on the other hand, a lack of understanding of A/B Testing statistics can cause unpredictable outcomes and errors.

There are eight aspects of A/B Testing statistics that you would have to deal with, and they include:

 Sampling, variance, and Mean

  • P-Values
  • Statistical significance
  • Statistical Power
  • Segmenting
  • Confidence intervals and margin of errors
  • Regression to the mean
  • Cofounding variables and external factors

These are terminologies that you can research more about to understand A/B Testing statistics better. You need to know them because they help you avoid mistakes and errors in test planning, interpretation, and execution.

Best A/B Split Testing Examples

For your business to succeed in today’s competitive environment, it must build a culture of scalable experiments. And although the content of your marketing campaign matters, you cannot take away the magic A/B Testing.

Below are some examples of successful A/B testing scenarios; it gives you a picture of how some leading companies worldwide are benefiting from the practice of A/B Testing.

#1 Example of A/B Split Testing

WorkZone is an email marketing software company based in the US, providing documentation collaboration and project management solution tools. It is a competitive industry, and they must be on their A-game to get conversions.

As part of building a good brand, they decided to add a customer review section close to the demo request form. However, they soon realized that this new section overshadowed the request form, thereby distracting customers on the page.

They decided to change their customer testimonial colors from the original colors to white and black. This change was to help them study if the number of demo requests would increase.

They ran the test for 22 days, and after that, WorkZone noticed that the Variation copy performed better than the original copy. They witnessed a 34% increase in the submitted forms, with a 99% statistical significance.

#2 Example of A/B Split Testing

Grene is an Ecommerce company in Poland that sells various comprehensive agricultural products. This company has carried out A/B testing on different occasions, which has led to the success of its brand.

One of such scenarios involved adding prominence to their in-page elements by revamping the mini cart page. After the company analyzed its mini cart page, they discovered that users were:

  • Users thought that the free delivery USP button was a clickable button where they could find extra details. But since it wasn’t a clickable button, it was causing some friction.
  • Secondly, users found it difficult to see the total for each product in the cart.
  • Users had to scroll to the bottom of the page to enable them to click the CTA button.

The company decided to make some changes by employing the A/B Testing tool. The following changes include:

  • To help users quickly access the main cart page, they made an additional CTA button to the top section of the cart page.
  • They also added a remove button to every item on the cart and the total amount of each product.
  • They made the CTA more pronounced to make it very visible.

The company ran this campaign for 36 days, and they witnessed the following results:

  • The visits to their cart page increased.
  • There was an increase from 1.83% to 1.96% in their Ecommerce conversion rate.
  • The number of their purchased items witnessed a 2x increase.

The Process for A/B testing 

Here are the steps involved in a successful A/B testing in email marketing.

Understand the things to test out first

Determine what you want to test first by looking at your analytics data or conducting interviews with potential customers to find out which version of a message is most compelling: Do people respond better when you’re saying “buy this now.” or “don’t miss our sale.”? 

You can also think about non-traditional ways to test your message. For example, if you’re trying to promote a time-sensitive offer, how would people respond when that offer is sent on Tuesday versus Thursday?

Set up an A/B testing system so you can track which version performs better by sending the same email with different subject lines or content to half of your recipients.

In any case, make sure both versions have similar layouts and colors for ease of tracking results. Alternatively, one could use plain-text emails as they are more simple and contain no formatting.

Test out different images of your product or service 

A slight variation of the images that you use, can also cause surprisingly different results so it might be worth testing this out as well.

Combining Email Marketing with SMS Marketing

We can’t conclude this article without mentioning SMS marketing and how well it fits with a well-engaged email marketing list.

The best part of any customer interaction is the opportunity to get in touch and build a relationship, and SMS marketing allows you to do just that.

Texting customers via SMS works, and it’s easier than you think.

SMS Marketing provides a chance for more engagement between businesses and their existing or potential clientele, while also catering to people’s constantly on-the-go culture. 

When you combine the power of A/B testing in email marketing and the power of SMS marketing, the sky is indeed the limit.

Always Do A/B Testing For Best Email Marketing Performance

The best way to get more from your email marketing campaign is by using A/B testing. You can even use this process in other areas of business, such as website design and social media advertising campaigns. After all, this is similar to getting people down a funnel to ultimately take the action that you want.

No matter what kind of business you have and which kind of emails you send, A/B testing can be of benefit.

When you’re looking at the all-important numbers generated through these tests, remember that they should be followed closely because this ensures better results for deliverability, open rates, clicks and ultimately getting more conversions out of your emails.

Premium capabilities Feels enterprise,
minus the price

All the features your business needs to acquire high-quality leads, grow sales, and maximize revenue from campaigns
using one simple dashboard.

Get Started For Free
shape 1
shape 2
shape 3