What is A/B testing in direct mail?

A/B testing in direct mail is the practice of mailing two or more versions of a piece, differing in one element such as the offer, headline, or format, to comparable random splits of the same audience so the version that drives the higher measurable response can be identified and scaled.

How it works

The mailing list is split into statistically comparable random groups. Each group receives a version that differs in exactly one variable, while everything else stays constant, so any difference in results traces to that variable. Responses are tracked through unique phone numbers, codes, or URLs per version, so each conversion is attributed to the version that produced it. The version with the higher response rate at a meaningful sample size becomes the control, and the next test challenges it on a new variable. Variable data printing makes it practical to produce these versions in a single press run rather than separate jobs.

When and why it is used

Marketers use A/B testing to replace opinion with evidence before committing a full budget to one creative or offer. Testing on a small split first protects the larger spend and compounds learning across campaigns, since each winning element carries forward into the next mailing. The most common variables tested are the offer, the headline, the format, and the call to action, because those move response the most. Mail Processing Associates produces over 10 million pieces annually, including split-version runs set up so each variant is tracked separately. For campaign setup and tracking, see our direct mail services.

Reviewed by the Mail Processing Associates production team, 35 years in business and over 10 million mail pieces a year.