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What Elements of Email Marketing Can Be A/B Tested?

There are so many strategies to implicate and understand, and knowing where to start can feel overwhelming. But, worry not, that’s where we come in.

We’re going to break down the ins and outs of A/B testing so you can breeze through email marketing in no time!

What is A/B Testing in Email Marketing?


Put simply, A/B testing is another way of saying a split test. It’s the process of sending two different versions of your email to other sample groups. The email, which then receives the highest open rate and click-through rate, aka “the winner”, is then sent out to the rest of your subscribers or email list.

More often than not, the importance of A/B testing will get overlooked by marketeers, mainly because they’re unsure of what actually to test. If you execute it correctly, you can drastically improve your metrics, increase conversions, understand the needs of your audience, find out what helps to drive sales and avoid winding up as spam mail.

What Should you be A/B Testing?


Not sure where to start with A/B testing? We’ve broken down four things you should be considering when you’re comparing data:


Subject Lines


Subject lines are essentially the bait to every email; they’re formatted with darker, heavier text, making it stand out in your inbox. You won’t get an effective open rate without a catchy subject line. In short, they’re essential in email advertising campaigns.

When it comes to email subject lines, clickbait is key - it’s a fine line to navigate; how do you create a compelling subject line without appearing too much like spam mail. We’ve picked out a few ways you can tests you can carry out on subject lines;

  • Length

    The length of subject lines is crucial for A/B testing via email marketing systems. Mobile devices show a different character length than a desktop, so it’s important to strike a balance in subject line length.

    According to Return Path, the golden character count for any email is between 41-50 characters or 5-6 words long. Specifically, anything over 35 characters can sometimes get cropped away in mobile email marketing. Testing the outcomes of different subject lines will highlight which length your business should be aiming for - and what your audience is more likely to click on.

  •  Word Order

    Every copywriter knows that word order can make or break an email. The order of the wording in a subject line can make a difference in how your audience will read and interpret your email. For example:

    “70% OFF your next purchase.”
    “Order your next purchase right now and take 70% off.”


    In the first example, the promotion is the first thing the recipient will see, compared to the second where the promotion gets hidden. Going forward, front loading the subject line with information will help to improve the click-through rate. Similarly, as well as word order, it’s beneficial to test the best time to send an email. Catching a consumer with a carefully timed email and structured word order is the ultimate way to drive conversions.

  • Personalisation

    Finally, another way to A/B test email subject lines is to add a touch of personalisation with syntax. Using a default message to include the recipient's name is a really impactful way of increasing the open rate of an email.

Tone of Voice

In email marketing, aside from A/B testing subject lines, another element always worth looking into is the overall tone of the email. According to a study, no matter what your brand, recipients respond better to positive emails with motivational messaging, which can increase conversion rates by up to 22%


Calls to Action 

Including a solid call to action within email marketing is crucial for the email's performance. By A/B testing your CTAs, you can find the most effective result! The best practices for email CTAs are;

  • Keep it Short

    The ideal call to action is 3-4 words; using any more than this could result in your recipient losing interest, especially on a mobile device.

  • Use the Right Language

    To hold the reader's attention, using the correct language is key. It would be beneficial to A/B test different actionable verbs such as “Buy now”, “Get it today”, and “Shop now”, etc, to see which verbs are most effective at captivating your audience and increasing the click-through rate.

  • Add a Pop of Colour

    Changing the colour of a call to action button is one of the most effective ways to A/B test. By using contrasting background colours and text, you’re more likely to make your CTA button “pop” on the page. When choosing a colour, try to avoid using yellow-blue and green-red colour combinations, as these tend to be the most difficult for the eye to process.

Images vs. No Images


Finally, another element of email marketing you’ll be able to A/B test is the content within the email. The first piece of content you’ll likely test will be images; do they improve the quality of the email or not? 

In a study, it was found that even though image-based emails look more aesthetically appealing, they often cause more harm than good. Over 43% of Gmail users have an image blocker installed on their mobile devices to cut out data use and loading time. The happy medium is for emails to have a balance of imagery and copy. Otherwise, you’ll risk your email being sent straight to spam or struggle with loading the email.



To sum up, A/B testing is extremely straightforward. In fact, email marketing is harder without A/B testing. Your campaigns won’t perform to the best of their ability without knowing what will improve them and what won’t.

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