July 19


When it Comes to Email Marketing, What Do We Mean by the Term A/B Testing?

By Hanson Cheng

July 19, 2023

  • minute read
  • Last Updated on July 19, 2023 by Hanson Cheng

    When it comes to email marketing, one of the most valuable tactics you can employ is A/B testing. But what exactly does this term mean? Put simply, A/B testing is a technique that involves comparing two variations of a single element in order to determine which one performs better. Email marketing typically involves testing different subject lines, calls-to-action, or other key elements to see which version generates more clicks, conversions, or engagement from your subscribers.

    What is Email Marketing?

    Email marketing campaigns are essential for businesses seeking to engage with their customers and keep them informed of their services. A/B testing, also known as split testing, is a method used in email marketing to compare two different versions of a message with the goal of identifying which yields the most favorable results.

    Specifically, A/B testing is a way to compare and contrast two different versions of an email campaign to see which one performs better. This testing can be performed on a wide variety of elements, such as the email’s subject line, layout, call to action, images, and copy. The results of A/B testing are used to optimize individual campaigns to increase user engagement, click-through rates, and conversion rates. By conducting A/B tests, businesses can uncover insights about what is driving engagement among their email subscribers while also gaining a better understanding of how certain email campaign elements resonate with their audience.

    As such, A/B testing is critical to building an effective email marketing strategy for any business that wants to maximize its reach and impact with customers.

    The Purpose of A/B Testing

    Before delving into the details of A/B testing for email marketing, it is important first to understand its purpose. The primary goal of A/B testing is to improve the effectiveness of marketing campaigns by systematically experimenting with different variables and identifying the combination that yields the best results. By testing multiple variations of the same email, marketers can gain valuable insights into what resonates with their audience and make data-driven decisions to optimize future campaigns.

    Furthermore, A/B testing is not limited to just email marketing. This methodology can be applied to various aspects of digital marketing, including website design, ad copy, and social media messaging. The versatility of A/B testing makes it an essential tool for any marketer looking to stay ahead of the competition and drive meaningful business outcomes.

    The Benefits of A/B Testing in Email Marketing

    A/B testing is a fundamental technique that allows email marketers to identify which elements of their email campaigns are effective, and which are not. By creating two variations of an email message and sending them out to two groups of subscribers, marketers can identify which version performs better in terms of open rates, click-through rates, conversions, and other key metrics. This process helps marketers to refine their email campaigns and increase their return on investment.

    Different Types of A/B Testing

    Subject Line

    The subject line is one of the most critical elements of any email marketing campaign. It’s the very first thing that your subscribers see, and it can make or break your campaign. That’s why it’s essential to test your subject lines to determine which ones are most effective. A/B testing is a powerful tool that allows you to test two different subject lines against each other to see which one performs better. There are numerous ways you can vary your subject lines to test them. For instance, you could try different lengths, tones, emojis or punctuation, or a different approach to the offer.


    One important aspect of A/B testing is the content used in the tests. The Content subsection of Types of A/B Testing is focused on this specific area of testing and aims to explore the different types of content that can be tested. One type of content that can be tested is the subject line of an email. The subject line is the first thing a recipient sees and can significantly impact whether or not they open the email. Another type of content is the email copy itself. Testing different variations of the copy can help improve engagement rates and ultimately lead to higher conversion rates.

    Images can also be tested in A/B testing, including the placement, size, and type of image used. Dynamic content is another type of content that can be tested. This type of content can be personalized based on the recipient’s previous interactions or behavior. Lastly, the call-to-action (CTA) is an important element of email content that can be tested. Testing different variations of the CTA text, color, placement, and size can help determine what drives the highest conversion rates. Overall, the Content subsection of Types of A/B Testing highlights the importance of testing different elements of email content to optimize engagement rates and improve overall performance metrics.


    A call-to-action (CTA) is a prompt that exhorts potential customers to take a specific action, which can include subscribing to a service, purchasing a product, or filling out a form. It is an essential component of digital marketing, including email marketing. CTAs in email marketing campaigns compel recipients to act, increasing engagement and conversion rates. By A/B testing CTAs, marketers can determine which CTA is more effective. Elements that can be A/B tested in a CTA include color, placement, and verbiage.

    For example, one can test a blue versus green button, a CTA at the email’s end versus within the email’s body, and a CTA that says “Buy Now” versus “Learn More.” By comparing the performance of two different versions of a CTA, marketers can determine which version positively impacted the campaign’s outcome and use that knowledge in future campaigns. Overall, A/B testing CTAs is a powerful tool allowing marketers to tailor their approach to their audience and optimize their email marketing strategy.

    Sender Name

    One important aspect of A/B testing in email marketing is testing different sender names. This involves choosing between using a person’s name or a company name as the sender of the email. The sender’s name is one of the first things recipients see when they receive an email, so it can significantly impact open rates and overall engagement. A sender name that is recognizable and trustworthy can increase the likelihood of a recipient opening the email.


    One significant aspect of A/B testing in email marketing is timing. Knowing the best time for sending out marketing emails can significantly impact the success of email campaigns. Therefore, A/B testing on the timing of emails is essential. Experimenting by sending the same email content at different times of the day or week can help determine when recipients are most likely to open and read the email.

    Factors such as the industry, target audience, and location can influence the best time to send emails, so it’s important to remember these factors while carrying out A/B tests on timing. Additionally, regularly testing the timing of email campaigns can help keep up with changes in consumer behavior and ensure that emails are being delivered at the optimal time for maximum engagement.

    How to Conduct A/B Testing

    Step 1

    Before delving into the specifics of A/B testing for email marketing, it is important to define what A/B testing is. The A/B testing strategy is a data-driven optimization technique that compares two versions of a marketing element, such as an email, landing page, or advertisement, to determine which one performs better. In email marketing, this technique involves sending two different versions of the same email to two randomly selected segments of subscribers.

    Step 2

    Once you have decided what you want to test and who your target audience is, the next step in A/B testing is creating the variation of the email you want to test against the control group. When designing your variation, you should remember your email’s purpose and message. The variation should not be drastically different from the control group in terms of look and feel. Minor changes are easier to identify and will provide more reliable results. Once you have created your variation, it’s time to set up your A/B test. You will need to determine the size of your test group and the length of time you want to run the test.

    A small test group may not provide statistically significant data, while a test that is run too long may lose relevance due to changes in external factors. You should also decide on the metric that you want to measure your success. This could be open rates, click-through rates, or conversion rates. Each metric will give you different insights into the effectiveness of your email, so choose the one that aligns with your goals.

    After you have set up your A/B test, you will need to send the variations to the appropriate groups and monitor the results. It’s important not to interfere with the test during the duration of the test. After the test has concluded, analyze the results and draw your conclusions.

    Step 3

    When it comes to email marketing, A/B testing is an important technique that can help businesses improve the effectiveness of their email campaigns. A/B testing involves creating two or more versions of an email and sending them to a small sample of subscribers. The goal is to determine which version performs better in terms of open rates, click-through rates, and other metrics. During the testing phase, it is important to only change one variable at a time, such as the subject line, the call-to-action, or the content of the email. Once the test is complete and a winner is identified, the winning version can be sent to the remaining subscribers.

    There are several key steps involved in conducting A/B testing for email marketing. The first step is to identify the goal of the test. This could be increasing open rates, click-through rates, conversions, or other metrics. The second step is to create two or more versions of the email, each with a different variable. For example, one version may have a personalized subject line while the other has a generic subject line. The third step is to send each version to a small sample of subscribers randomly selected from the email list. The fourth step is to track and analyze the results of the test, looking at metrics such as open rates, click-through rates, and conversions. Finally, the winning version can be sent to the remaining subscribers once a winner is identified.

    Step 4

    One of the most important aspects of conducting effective A/B testing for email marketing is analyzing and interpreting the data acquired in the process. After creating and executing the test, it’s time to dive into the results and determine what they mean for your marketing strategy going forward. The first step in this process is comparing the two test groups and identifying any significant differences in engagement rates, click-through rates, and overall conversion rates.

    It’s also crucial to leverage tools and resources that help you analyze and interpret the data effectively. This could include data visualization software, statistical analysis tools, or even consulting with industry experts who can offer insight based on their experience. With the right data analysis techniques and tools, you’ll be able to uncover meaningful insights that can inform your marketing strategy moving forward and drive better results in the future. In addition to analyzing the data, it’s also important to document and track your findings, which can be used to inform future A/B tests and marketing campaigns.

    Finally, it’s important to emphasize the importance of ongoing testing and optimization, to ensure that your email marketing efforts continue to evolve and improve over time. By regularly conducting A/B tests and analyzing the results, you’ll be able to stay ahead of changes in the market and continually refine your approach to email marketing. With the right approach to A/B testing, data analysis, and ongoing optimization, you can maximize the effectiveness of your email marketing campaigns and drive meaningful results for your business.

    Step 5

    After creating your hypotheses and setting up your A/B test, monitoring your results and analyzing the data is essential to draw meaningful conclusions. To begin with, make sure to give your test enough time to run to avoid hasty conclusions based on limited data. The duration of your test depends on the size of your email list and the number of variants you are testing. With more significant traffic, the test will conclude faster. Once you have appropriate data, you can start analyzing the results to determine which variant performed better.

    Conducting A/B testing in email marketing is crucial to understand your subscribers’ behavior and preferences to optimize and improve your email campaigns. The process may seem daunting, but it’s worth it. By testing different variables, you can identify which elements resonate with your email subscribers and make data-driven decisions that lead to better results. Whether it’s testing subject lines, calls to action, or email design, A/B testing helps identify improvement areas that can enhance your email marketing efforts. However, it’s important to recognize that A/B testing is not a one-stop-shop but an iterative process that requires continuous optimization to achieve the best results.

    Best Practices for A/B Testing

    Test One Element at a Time

    Email marketing is an essential tool for businesses to engage with their customers. However, it can be challenging to stand out in a world where people are inundated with emails. This is where A/B testing comes in. One of the best practices for A/B testing is to test one element at a time. This means that when conducting an A/B test, businesses should only change one variable in the email. For instance, if a company wants to test an email’s subject line, they should only change that element and leave the rest of the email the same.

    Testing one element at a time allows for accurate results by understanding what variable changes produce the desired outcomes. By changing multiple elements at once, businesses cannot determine which element produced the desired outcome. Additionally, testing one component of an email at a time is a more efficient way to run A/B tests as it allows a business to complete tests more quickly. Moreover, conducting tests in this manner ensures that any changes made to email campaigns are based on data rather than speculation.

    Overall, testing one element at a time is a crucial best practice for A/B testing, and following this approach can help businesses achieve better results in their email marketing campaigns.

    Test a Large Enough Sample Size

    One crucial aspect of effective A/B testing is testing a large enough sample size to ensure statistical significance. Statistical significance is essential in ensuring that the results obtained from A/B testing accurately reflect the behavior of the population or audience being tested. One important reason for ensuring a large enough sample size is to reduce the chance of obtaining a false positive result.

    False positives occur when there appears to be a significant difference between the test and control groups, but in reality, the difference is due to chance. To avoid a false positive, it is important to have a large enough sample size to ensure that any differences observed between the two groups are not the result of chance but rather the actual difference in response to the treatment.

    It is also important to consider the level of significance required when A/B testing. The level of significance refers to the probability of obtaining a false positive result, often expressed as a percentage. The industry standard for the level of significance in A/B testing is typically 95%. This means that if the results show a difference between the test group and the control group, the probability of this result occurring by chance is no more than 5%. However, depending on the experiment’s nature, a lower significance level could be acceptable.

    Another consideration when testing a large enough sample size is the size of the effect that is considered significant. The effect size refers to the magnitude of the difference between the two groups being tested. The larger the effect size, the smaller the sample size required to achieve statistical significance. However, if the expected effect size is small, a larger sample size is usually needed to detect any difference between the test and control groups.

    Set a Clear Goal

    One of the essential components of a successful A/B testing strategy is setting a clear goal. Without a well-defined objective, it is challenging to measure success accurately. Therefore, it is crucial to establish a goal that aligns with your overall marketing strategy. Ask yourself what you want to achieve from the test. Do you want to increase your open, click-through, or conversion rates? Perhaps you want to identify the best-performing subject line or the optimal send time for your email campaign. Whatever it may be, ensure that it aligns well with your overall objectives.

    Test Regularly

    Email marketing is a constantly evolving field, and to stay ahead of the curve, A/B testing is crucial. A/B testing allows marketers to experiment with the different components of an email, such as subject line, design, and CTA, in order to gauge the best practices for maximizing engagement and conversions. However, it is important to note that A/B testing is not a one-time process.

    It requires consistent testing and optimization to keep up with changing consumer behavior and industry trends. Regular testing helps ensure that emails are relevant, personalized, and effective. By analyzing the results of A/B tests, marketers can identify patterns and insights that can inform future campaigns and improve overall performance. Thus, making it paramount that businesses make a habit of testing regularly.


    Email marketing is a powerful tool for businesses of all sizes seeking to connect with their customers. One of the most effective ways to improve recipient engagement is to perform A/B testing on email marketing campaigns. A/B testing is a process of testing two different versions of an email campaign against one another to see which performs better. The goal of A/B testing is to make data-driven decisions, measuring the impact of individual components of an email, such as subject lines, images, calls to action, and more.

    Through the testing of these elements, businesses can determine the factors that drive higher open and click-through rates, optimize their campaigns accordingly, and ultimately boost conversions. Marketers should carefully plan and execute A/B testing, considering which metrics to track and how to measure the success of each test. By continually refining and optimizing email campaigns, businesses can drive higher engagement rates, increased revenue, and a stronger relationship with their subscribers.

    Future Outlook

    As we move into the future of email marketing, it’s clear that A/B testing will continue to play a critical role in optimizing conversion rates and achieving success. With the rise of personalization, automation, and AI-powered tools, businesses will have even more sophisticated methods for segmenting their audience, tailoring their messages, and testing the impact of different variables. The use of machine learning algorithms and predictive analytics will enable marketers to rapidly iterate on their campaigns and make data-driven decisions that drive measurable results.

    However, as technology becomes more advanced, it’s important that email marketing professionals don’t lose sight of the fundamentals of A/B testing. They should continue to focus on testing one variable at a time, ensuring statistical significance, and using clear, actionable data to inform their decisions. They should also remember that A/B testing is just one piece of the email marketing puzzle. That success ultimately depends on creating compelling content, building strong relationships with customers, and delivering value with every interaction. With these principles in mind, businesses can use A/B testing to drive engagement, boost revenue, and achieve long-term growth.

    A/B Testing and Email Marketing – FAQs

    What is A/B testing in email marketing, and how does it work?

    A/B testing, also known as split testing, compares two versions of an email campaign to determine which one performs better. By sending two variants of the same email to a small segment of your audience, you can identify which version drives higher open rates, click-through rates, conversions, and other key metrics. You can then send the winning version to the remaining audience for better results.

    What are some common elements to A/B test in email marketing?

    The most common elements that email marketers test in A/B testing are subject lines, from names, preheaders, send times, layouts, images, CTAs, and copy. By changing one of these variables at a time, you can isolate the impact of each element on email performance and optimize the overall effectiveness of your campaigns.

    How long should an A/B test run in order to produce reliable results?

    The ideal duration for an A/B test in email marketing varies depending on factors such as the size of your list, the frequency of your mailings, and the metric being tested. However, most experts recommend running tests for at least 24-48 hours until you have a statistically significant sample size of 1,000-2,000 recipients per variant.

    Can A/B testing help improve email deliverability and engagement rates?

    A/B testing is a powerful way to optimize your email campaigns for better deliverability, engagement, and ROI. By identifying the subject lines, content, and other variables that resonate with your subscribers, you can tailor your messages to their preferences, improve engagement rates, and ultimately boost the chances of your emails landing in the inbox instead of the spam folder.

    What are some best practices for conducting A/B testing in email marketing?

    Some best practices for A/B testing in email marketing include testing only one variable at a time, segmenting your audience based on past behavior or demographics, using a randomized sample for each version, analyzing the results in a statistically valid manner, and using the insights to inform future campaigns. Moreover, it’s recommended to test regularly, as changes in the market and your subscribers’ preferences can affect the performance of your campaigns.

    What are some pitfalls to avoid when performing A/B testing in email marketing?

    Some common mistakes to avoid when conducting A/B testing in email marketing include not having a clear hypothesis or strategy, testing too many variables at once, not testing long enough, not segmenting the audience appropriately, drawing conclusions from low sample sizes, and ignoring non-email factors that might influence your results. To ensure valid and actionable results, having a well-defined testing plan is crucial, using reliable tools, and interpreting the data with statistical and contextual rigor are crucial.

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    Hanson Cheng

    About the author

    Living in Portugal with my wife and puppies.
    Scaling online businesses and sharing lessons learned on this website and in our email newsletter.

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