A/B testing (also called split testing) is the practice of sending two versions of an email to small, comparable parts of your list to see which performs better, then sending the winning version to everyone else. It replaces guesswork with evidence about what your subscribers actually respond to.
What you can A/B test
Common variables are the subject line, sender name, send time, call to action, layout, and images. Test one variable at a time so you know what caused the difference. Subject lines are the most common starting point — see our tips on writing the ideal subject line.
How to run a clean test
Pick one metric to judge by (often open rate for subject lines or conversion rate for content), use a large enough sample to be meaningful, and let the test run long enough to be reliable. Our guide walks through it: test your campaigns with A/B testing.
Why it matters
Small, repeated A/B tests compound into significantly better results over time. Related: email subject line and call to action. See subject line best practices in Mailpro.
Mailpro and A/B testing
Send the version that actually wins
Test subject lines and content on a sample, then let Mailpro send the winner to the rest — better results without the guesswork.