A/B testing compares variations to assess a chosen outcome. Mailchimp’s testing guidance describes changing one variable type, such as an email subject line. Variations are distributed randomly among test recipients. That structure helps make the comparison clearer than changing several unrelated things together. Source: Mailchimp: About A/B tests

Write the question first

For a travel newsletter, an illustrative question might be whether a specific destination subject line produces more recorded clicks than a broader holiday subject line. Agree the outcome, audience and test period before sending. Keep the rest of the message consistent, so the question and the change remain aligned.

Keep the conclusion proportionate

Record the variation, recipient counts, results and decision. If there is little evidence or the outcome is unclear, say so and retain the learning for another test. This makes the exercise useful without presenting a small difference as a permanent rule for every audience or campaign.

Written and updated by Travelgenix. Sources checked on 16 October 2026. Worked examples and recommendations are editorial illustrations, not customer results.