The most critical factor of email marketing

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Frustrated about not getting the results you are aiming for when deploying emails? Do you have low open, click through and conversion rates, and aren’t sure why? A/B testing can identify what works the best for you, which can help you achieve optimal results.

A/B testing or split testing emails is an effective way to work out which subject line, email content, sending time or From Address will get you the results you are after. Despite the value that A/B testing provides, only a frightening 16% of marketers take advantage of it, hence the remaining 84% are wasting their resources on ineffective email marketing*. A/B tests are quick to implement, will produce a greater email ROI and empower you to reach your KPI’s. For more on email marketing, checkout our information on best practices here.

There are many items you can test before sending out an email, most commonly the subject line, content, sending time and From Address. In A/B testing there are generally 2 versions of what you are testing, that communicate the same message. The number or percentage of subscribers that will receive version A is generally 15-25% of your database, another 15-25% receives version B and the remaining 50-70% receive the version that performed best. When using a small sample, keep in mind the smaller the sample the less valid and reliable results can be. Ensure that at least 1000 subscribers have chosen the end result that you decide to implement.


Top tips for A/B tests:

Subject Line

When testing a subject line for an email, start off with one subject line and adjust it to a second one. These differences can be the wording, statistics or emojis used. This will now form your version A and version B for testing the subject line. These slight differences severely impact on the open rate of an email.

Here is an example of how to test a subject line on Adestra**:



If you don’t have Adestra, or just want to use another method of testing, you can go to to receive a score for your subject line. If the score over 80, you are on the right track.

From Name/Email address

It is worthwhile verifying whether your readers better engage with your name, company or brand using A/B tests. The From Address and From Name can change the way readers react. For example, in B2B contexts professionals tend to better react to a person’s name than a company name while in B2C, consumers react more positively to a company that they recognise and know.

Content/call to actions

Within the email itself, you can also test which content or call to action has the best reaction through assessing the click through and the conversion rate. For links that give more content, the click through rate is used, and for links where you would like the subscriber to purchase something or trial a product, a conversion and/or click through rate should be assessed. For example, you may test the call to actions, to determine which sized button is best:
A: Large button
B: Smaller button


Sending times

To determine the best deployment time for your target audience, send the same email across two or three key times and assess which does best overall. For example, send the email to 20% of your database at 9am, and send the email to 20% of your data base at 5pm and see which one performs best. The best performing time will then be used to send the remaining 60% of your database the email.

Guidelines to consider whilst A/B testing:

  • Only do one test at a time, as you shouldn’t run A/B testing on a subject line and on call to actions at the same time
  • Your testing time is very important to factor in. We recommend running the test until you have a clear result with a valid sample size. If you do not have a clear result, this means that the two versions are too similar or the audience responds the same to both.
  • In regards to sample size, as previously mentioned ensure that at least 1000 subscribers have chosen the end result that you elect to implement.


And that’s it! Start using A/B testing and get the results you are after. In no time your open, click through and conversion rates will increase and your performance will reach new heights.


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