A/B testing lets you create two versions of the same sequence (A and B) so you can compare performance and keep the variant that gets the best results.
Learning objective
By the end of this tutorial, you’ll know how to create an A/B test for a lemlist sequence, build two variants, and choose a winning version.
Why this matters
Small changes like messaging, timing, or sequence structure can significantly impact performance. A/B testing helps you validate what works with your audience using real campaign data instead of guessing.
Prerequisites
You already have a campaign with a sequence created.
You know which element you want to test, such as copy, delays, or sequence structure.
Core lesson — step-by-step workflow
Phase 1: Create your A/B test variants
Go to Campaigns and open the campaign you want to test.
In the campaign builder, make sure you are in the Sequence tab, then click the A/B test icon.
Choose how you want to create Variant B:
Duplicate Variant A to copy the current sequence and make small changes, or
Start from scratch to build a completely different version.
Then click Create variant B.
Once Variant B is created, use the tabs at the top of the sequence builder to switch between Sequence A and Sequence B, then edit the version you want to test.
(Optional) Remove Variant B
If you want to stop building the test before launch, open the three-dot menu on Sequence B and click Delete variant.
Phase 2: Decide what to test
For a clean test, change only one major variable at a time. The more differences you introduce, the harder it is to understand what caused the result.
Content tests: subject line, CTA, opening line, personalization, or offer positioning.
Structure tests: first step type, wait times, channel order, or number of steps.
Practical application (recommended approach)
Pick one hypothesis: for example, “A shorter first email will get more replies.”
Keep everything else consistent: same lead list, same sending window, and similar campaign duration.
Create your A/B test before launching: this gives both variants the best chance to split leads cleanly.
Run the campaign long enough to collect meaningful results before deciding on a winner.
Choose a winner (stop A/B testing)
Important: Choosing a winner is irreversible. Once you choose the winning sequence, A/B testing is stopped and the choice can’t be undone.
When you're ready to stop the test, open the three-dot menu on the variant you want to keep and click Choose as winner.
Read the warning, then click Confirm to apply your choice.
Troubleshooting & pitfalls
Issue: Results are inconclusive
Root cause: Not enough leads or not enough time running.
Fix: Increase sample size, run the campaign longer, or simplify the test to one variable.
Issue: You changed too many things between A and B
Root cause: Large differences make it hard to identify what improved performance.
Fix: Test one variable at a time, then iterate from the better-performing version.
Issue: You want to stop the test later
Root cause: You found a better-performing variant and want all future leads to receive it.
Fix: Use Choose as winner to end the test and keep the winning version.
Review results and pick a winner
After your campaign has collected enough data, compare the results of Sequence A and Sequence B, then keep using the better-performing version in future campaigns.