What is A/B testing in email marketing?

A/B testing (also called split testing) is an experimental method where you send two different versions of an email to separate segments of your audience and measure which performs better.

Version A serves as the control. Version B contains one specific change, such as a different subject line, CTA button, or send time. By comparing results between the two groups, you identify which variation drives better outcomes.

Effective A/B testing requires a clear hypothesis, a single variable change, and sufficient sample size to achieve statistical significance. Testing multiple elements simultaneously makes it impossible to isolate what caused any difference.

A/B testing transforms email marketing from guesswork into science. Instead of assuming what your audience wants, you measure it directly and let data guide your decisions.