A/B Testing Email Campaigns: What to Test and How

A/B testing email campaigns with performance chartsTesting

Priority order for most teams: subject line → offer/CTA → send time → hero image → body copy length.

What to Test First

Priority order for most teams: subject line → offer/CTA → send time → hero image → body copy length.

Change one variable per test. Multivariate tests need larger lists to reach significance.

Sample Size and Confidence

Send the test to 20–30% of the list, wait 4–24 hours, then send the winner to the rest. Small lists need longer run times.

Do not call winners on tiny differences — look for meaningful CTR lifts.

Document and Compound Wins

Keep a test log: hypothesis, result, date, segment. Winning subject line patterns inform SMS and ad copy too.

Quarterly reviews reveal creative fatigue — refresh what stopped working.

Frequently Asked Questions

How long should an email A/B test run?

Usually 4–24 hours depending on list size and send window.

Can I test multiple subject lines?

Yes, with A/B/C tests if your platform supports it and audience is large enough.

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