When marketers design websites, draft emails and write calls to action, they often create by intuition. But rather than relying on creative assumptions, strong marketers put their best ideas to the test. Split-testing or a/b testing direct mail marketing content is the only way to truly know what will make people convert.
With emails, one of the most tested variables is a different subject line. Social media ad managers would often put to test the banner design. While a/b testing direct mail may take a few more steps than split-testing digital marketing, it is just as important. You can use a/b testing to guide your direct mail decisions and improve the overall marketing campaign results. It will just take a little planning.
In this post, we’re going to walk you through 3 ways to split-test direct mail. (You can find out exactly how to run a direct mail a/b test using Inkit here.)
3 Split Test Mailer Ideas for Your Next Direct Mail Campaign
Running effective a/b experimentation on direct mail doesn’t have to be very complicated. Here are a few traditional direct mail examples to split test your next direct mail testing strategy:
A/B Direct Mail Test #1: Single variable split-test
This is what most people think of when talking about split-tests. In a single variable direct mail test, you create one mailer, duplicate it, and edit one single item on the b-copy. In this type of split-test, everything except for the test variable needs to remain identical. You then randomize and split your direct mailing list so that one version goes to half your audience and the other version to the other half. In most cases, a single variable direct mail test is the ideal method because it makes it very clear why your audience reacted a certain way. If you were to test two completely different postcards, on the contrary, which elements inspired action would not be evident.
When deciding which variable to split-test in direct mail, consider:
- Different offers, such as a discount + free shipping vs. greater total discount amount or a discount vs. a sign-on bonus or free gift
- Different presentations of the same offer, such as different expressions of the same discount (such as dollars off vs. percent saved), call-to-action copy, headline copy and eye catching design
- Various direct mail formats (marketing postcard sizes)


For inspiration, review some of the proven postcard design and copy best practices. If you want your direct mail piece to grab your customers’ attention as soon as they open a mailbox, experiment with different postcard sizes, colors and graphics of your postcards, as well as an envelope (or a lack of one) and personalization approach.
Click here to learn how to split-test postcards with Inkit.
A/B Direct Mail Test #2: Existing/prior campaign control group test
In this type of test, your “A” mailer is one that you have sent before. You will create a new “B” postcard to test against it. “B” can be completely different than A, with many variables, or you may still decide to test a single variable for better clarity in results. Like in the previous test method, you would split your direct mail list in half, sending one group the control postcard and one group the new postcard. This is a method to continually improve an on-going direct mail campaign (like an onboarding or ‘welcoming a new customer’ campaign, where you get a continuous influx of new contacts into your CRM list).
Remember to make sure that each half of your direct mail list that’s being tested receives only one type of a mailer (“A” or “B” only) during the test period, and is not subjected to multiple direct mail or digital campaigns at the same time. Otherwise, you won’t be able to properly track the performance.
Pro tip: if you automate direct mail using triggers, consider running a control test from time to time to in order consistently enhance campaign performance as your audience changes and grows.