What is A/B testing, and what should we test first?

A/B testing compares two variants with real recipients rather than debating which one is best.

Test one thing at a time

If you change both the subject line and the content, you won't know what worked. The whole point is to make one change per test.

Start with the subject line

It determines whether the email is opened at all, and it is the quickest thing to test. You can then test buttons and content.

The volume must be large enough

With two hundred recipients, the difference is down to chance. Several thousand per variant makes the result actionable.

Measure what matters

Open rate is easy to measure but tells you little. Clicks and actual conversions are what matter. One variant can win on opens and lose on sales.