A/B Testing Strategies for Email Campaign Optimization

20 mins read

In the fast-paced world of digital marketing, the ability to make data-driven decisions is paramount. Email marketing, with its direct line to consumers, offers a treasure trove of possibilities for communication. In addition, it also provides excellent opportunities to improve that communication and find ways to talk to your customers most effectively. 

In this article, we’ll cover the possibilities of A/B testing – a tool that sharpens that edge, allowing marketers to understand and capitalize on consumer behavior. 

Email Marketing: The Digital Megaphone

Email marketing stands as a cornerstone in the digital marketing landscape. It’s a personal channel that can yield significant financial benefits. In fact, in terms of ROI (Return on Investment), email marketing outperforms all other digital marketing strategies with an average return of $36 for every $1 spent. By crafting personalized content delivered straight to an individual’s inbox, businesses establish a direct and measurable line of communication with their clientele. Different metrics offer good opportunities for analysis in email marketing, and one of the most noteworthy ways to strengthen your content is to conduct A/B tests. 

The Evolution of A/B Testing

A/B testing, a method with a rich history, has become a linchpin in the marketing world, offering insights and strategic direction for campaigns. It’s difficult to pinpoint the precise origin or “birthday” of A/B testing, but some of its roots can be found in agricultural experiments of the 1920s and the development of marketing strategies in the 1960s. 

The introduction of A/B testing into email marketing coincides with the digital revolution and the rise of the internet in the late 20th century. Google’s role in bringing A/B testing to the digital forefront is a pivotal chapter in the history of this methodology. In the early 2000s, Google began using A/B testing to enhance its user interface and search algorithms. One of the most known examples happened in 2009 when Google tested 41 shades of blue for its ad links to determine which color resulted in the highest click-through rate. This method of empirical testing quickly spread across the tech industry, and companies started recognizing the power of making decisions based on data rather than intuition. 

A/B Testing in Email Marketing: Benefits Unveiled

A/B testing is more than a marketing tactic; it’s a strategy that reveals the nuances of customer preferences. It clarifies what resonates with audiences, providing clear insight to understand the client landscape better and learn how to craft messages that hit the mark. In email marketing, A/B testing is a game-changer. Marketers can significantly increase email open and click rates and overall engagement by systematically testing and analyzing different components in their emails. To boost the effectiveness of your campaigns, delve deeper into the elements you can test and glimpse at some examples for inspiration.   

The A/B Testing Canvas: Email Elements in the Spotlight

Each element plays a critical role in the success of an email campaign. Through A/B testing, these components can be fine-tuned to perfection, each one offering a new opportunity to connect with the reader. Below, we’ll dissect these crucial parts, exploring how they can be tested and optimized for maximum engagement. 

Subject Line and Preheader

The subject line is the first impression – an email’s handshake with the reader. A compelling subject line can drastically improve open rates. Testing might involve a direct, offer-driven approach against a more mysterious, curiosity-sparking phrase. For instance, a Black Friday campaign could test “Unlock Your Black Friday Exclusive Discount” versus “Is the Best Black Friday Deal Inside?” Similarly, preheaders complement the subject line, providing additional context or urgency that can influence the reader to open the email. Another popular thing to test is the use of emojis – whether they work for your specific audience and, if so, what kind of emojis to use. 

Here, we have highlighted both elements simultaneously, but to see the exact performance of either the subject line or preheader, you can test them separately – for example, only the variants of the preheader, whereas the subject line remains the same. 

Test example #1:

  • Variant A: 

Subject Line – Exclusive Summer Collection Just Launched – Dive In! 🌊☀️

Preheader – Be the first to explore our new arrivals.

  • Variant B: 

Subject Line – A Fresh Take on Summer: Discover What’s New!

Preheader – Your perfect summer wardrobe awaits.

Test example #2:

  • Variant A: 

Subject Line – You’re Invited: Exclusive VIP Event Just for You! 

Preheader – Join [company’s name] for an unforgettable evening of surprises and special guests.

  • Variant B: 

Subject Line – Ready for a Night to Remember? 🎉 Special Invitation Inside.

Preheader – Secure your spot at [company’s name] once-in-a-year VIP gala event!

Test example #3:

  • Variant A: 

Subject Line – We Saved Your Cart For You 🛒

Preheader – Items in your cart are selling fast. Secure them now! 

  • Variant B: 

Subject Line – Forgot Something? Your Cart Misses You! 🛒

Preheader – Don’t worry, we’ve saved it for you!

Email Copy

The body of an email is where the story unfolds and your brand’s message is conveyed. The way you write the copy is crucial. Are you using a professional and formal approach, or do you keep your messages conversational and casual? This choice depends largely on your field of activity and can resonate differently with various audiences. The selection of words and tone offers many different details to experiment with and options to choose from. 

For a recruitment company, the tone could shift from corporate to community-focused, testing which better attracts potential candidates. You may be about to launch your monthly newsletter, or you’re just making refreshments in your brand communication. Testing the content will help you determine the final tone to go with. Also, testing various subheadings inside a promotional email can give you an idea of which works better in attracting attention – for instance, specific and conventional subheadings or witty and daring ones. Finally, A/B testing can help when your team can’t decide whether to use the long or short version of a paragraph in the email copy. 

Test example #1:

  • Variant A: A professionally toned introduction and bullet-pointed benefits before the CTA.
  • Variant B: A friendly toned introduction with a success story before the CTA. 

Test example #2:

  • Variant A: An inspiring, uplifting tone focusing on personal growth and well-being. Headline: “Embark on a Journey to Wellness – Transformative Health Awaits!
  • Variant B: A factual, informative tone providing clear benefits and health advice. Headline: “Achieve Health and Harmony – Practical Tips for Your Well-Being.

Test example #3:

  • Variant A: A grateful, community-focused closing that emphasizes collective effort, ending with a customer testimonial. 
  • Variant B: A more direct, sales-oriented closing with a sense of urgency. “Don’t miss out on our exclusive deals! Check out our latest arrivals and special offers today. Transform your space while supplies last!

CTA (Call-to-Action)

The CTA is the pivotal point of action in an email. It’s where you guide the reader to the next step, be it making a purchase or learning more about a service. Test different wordings, colors, and placements to see which drives higher click-through rates. 

Test example #1:

  • Variant A: A prominent “Buy Now” button at the top and bottom of the email.
  • Variant B: A more subtle “Find Your Deal” link placed midway through the content.

Test example #2:

  • Variant A: Placing the CTA button at the top and bottom of the email.
  • Variant B: Placing the CTA button midway through the content.

Test example #2:

  • Variant A: Red CTA button.
  • Variant B: Blue CTA button.

Source: Freepik

Header Image and Other Visuals

Visuals can instantly attract attention and set the tone of an email. A/B testing can reveal preferences for lifestyle imagery versus product photography or minimalist design versus detailed illustrations. For example, an outdoor apparel brand could test a hero image of adventurers in nature versus a clean product image against a white background. You can also add GIF-s to the mix or test our use of different typography in the images of your emails.

Test example #1:

  • Variant A: A vibrant header image showcasing people using the product in a real-life setting.
  • Variant B: A sleek header image with the product highlighted against a solid color background.

Test example #2:

  • Variant A: Using a static and clear image to showcase your clothing brand’s new seasonal collection.
  • Variant B: Using an animated GIF to showcase your clothing brand’s new seasonal collection. 

Test example #3:

  • Variant A: Using an elegant font in an image linked to your webpage. 
  • Variant B: Using a bold and playful font in an image linked to your webpage. 


Many promotional emails contain pictures with short descriptions, prices, and direct links to various products. These emails can be personalized to display products based on a recipient’s previous searches or purchasing history. However, if personalization is not possible, you have specific active discounts, or you need to promote a distinct group of products, you can add them to your email. Here, you can use the help of A/B testing to determine which products to pick, how many to display, and where to place them in order to maximize those clicks (and purchases). 

Test example #1:

  • Variant A: Adding the most popular products from the discounted goods to the email. 
  • Variant B: Adding the products with the most significant discount to the email. 

Test example #2:

  • Variant A: Displaying three products next to each other, placed in one row. 
  • Variant B: Displaying four products in two rows, with both pairs placed side by side. 

Email Layout

Talking about placement – testing different layouts, such as a single-column versus a two-column design, can affect readability and engagement. You can find out what resonates better with your subscribers and the type of your newsletter or marketing email with the help of A/B testing. 

Test example #1:

  • Variant A: A structured layout with a professional tone and bullet-pointed benefits, followed by testimonials.
  • Variant B: A narrative-driven layout with a friendly tone, starting with a success story followed by a call-to-action.

Test example #2:

  • Variant A: Blog post promotions appear sequentially below each other in the monthly newsletter.
  • Variant B: Blog post promotions appear next to each other in separate columns in the monthly newsletter.

Timing and Frequency

Ah, the good old question of when to send out those emails… What time is best, what day is best? Maybe you’ve even wondered what the most reasonable frequency could be. In addition to the visual elements that could undergo A/B testing, it’s also possible to test these strategically important aspects of your campaigns. 

Test example #1:

  • Variant A: Sending a sales campaign email just before lunch hour starts. 
  • Variant B: Sending a sales campaign email just before the workday ends. 

Test example #2:

  • Variant A: Sending the abandoned cart email right away. 
  • Variant B: Sending the abandoned cart email the next day. 

Test example #3:

  • Variant A: Sending out 5 emails within a drip campaign. 
  • Variant B: Sending out 3 emails within a drip campaign. 


In each case, it’s vital to measure the right metrics to ascertain success – whether it’s open rates for subject lines, click-through rates for CTAs, or engagement time for different design elements. Utilizing analytics tools, marketers can measure these metrics to determine which variant outperforms the other. This data-driven approach ensures that every email sent is an optimized communication crafted to engage, convert, and retain customers. 

Before conducting the test on a specific element, you must ensure that the other email components remain identical in both A and B variants. For instance, If you are trying to test the best CTA color for your email, it’s important to check that this is the only element that differs in email A and email B. By doing so, you can be confident that you are testing only what you intend to test, and that outside factors are not influencing the results. 

Here is an action plan to follow for conducting your A/B test:

  1. Determine the element you want to test. 
  2. Set a clear hypothesis for your test and define your success metrics in advance. This will help you accurately measure your test’s impact and make data-driven decisions based on the results. 
  3. Create two versions of your email, each with a different variation of the element you want to test. 
  4. Send both versions of the email to two separate, random subsets of your audience. Emailing a large enough sample size is essential to ensure that your results are statistically significant. You can use a sample size calculator to identify the needed number for your audience. If you have the advantage of a bigger mailing list, you can follow the 80/20 rule: send version A to 10% of the mailing list and version B to another 10% of your mailing list. 
  5. Track the performance of each version on your email marketing platform. Look for metrics such as open rates, click-through rates, and conversion rates to determine which version of your email performed better. 
  6. After discovering the best variant, send it to the rest of your mailing list. For example, if you follow the 80/20 rule and variant B has delivered better results, then send email variant B to the remaining 80% of your mailing list. 
  7. Prepare to enjoy better statistics from your email campaign! 

Source: Freepik

Additional testing considerations include external factors like seasonality, more detailed audience segmentation, and market trends. These can influence the effectiveness of an email campaign and should be accounted for when analyzing results. If you’re testing two different aspects of your email (other than timing), ensure that both email versions are sent simultaneously and on the same day of the week. 

In Summary

A/B testing in email marketing is an invaluable strategy that provides insight into consumer behavior, allowing you to refine your approach and maximize the effectiveness of your campaigns. In essence, you can test anything you can think of – whatever element or detail you want to include in your email and however you wish to design and automate it. 

By embracing this data-centric tactic, businesses can ensure that their message is not just heard but also resonates with their audience. The exciting thing is that A/B testing allows you to discover so much about your audience and benefit greatly from this fantastic possibility. Make sure to use it to the fullest, and may you have great campaigns to come! 

About the Author

Laura Bachmann is the Copywriter at Smaily – an intentionally simple email marketing and automation tool, rated as one of the top free email marketing software on Capterra. Smaily stands out by offering extraordinary direct customer support, excellent quality, and affordability for those seeking unlimited, expert-backed prospects for their email marketing pursuits. 

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