A/B test a subject line
Let Mailbo find the subject that gets more opens, automatically.
An A/B test (or "split test") sends two different versions of your campaign to small slices of your audience, sees which performs better, then sends the winner to everyone else — automatically. The most common use is testing subject lines to lift your open rate.
How it works
- Build a campaign as usual.
- Turn on A/B test and create variants — e.g. two different subject lines (Variant A and Variant B) for the same email.
- Mailbo sends each variant to a portion of your audience.
- After a set time, it picks the winner (the variant with more opens or clicks) and sends that version to the rest of your list.
What to test
Test one thing at a time so you know what made the difference:
- Subject line — the most impactful and the easiest to test.
- Sender name, or the preview/preheader text.
Changing several things at once tells you that something worked, but not what.
Reading the result
When the test finishes, the campaign report shows each variant's open and click rates and which one won. Use that lesson on your next campaign — over time your subject lines get sharper.
Tip: A/B testing needs enough people to give a reliable result. On a very small list (a few dozen contacts) the difference is mostly noise — it pays off most once you have a few hundred-plus subscribers.