Many of our customers have been waiting for AB testing and it’s finally live and can be used on our free plan. You can use subject line AB testing on Bulk/Marketing Campaign type only, not on automations or transactional campaigns.

What Is an A/B Test Campaign?

An A/B test campaign is a campaign with 2 or more versions being tested on one dimension – typically subject line or send time. A multi-variate test is a test with more than 1 dimension, for example if you are testing 2 different subject lines with 2 different versions of your message body you have 4 total versions and a multi-variate test, to determine the best combination of subject line and message body.

AB test results

Why Use AB Tests?

AB tests can help you optimize your campaign engagement, by determining best time or subject line to use. If you have a large list (over 50k) you can test a subject line on 20k and then use the best one on the rest of your list, improving your engagement overall.

You can setup AB test to determine:

  1. Ideal send time for your brand or list – test early on, then use that knowledge forever!
  2. Best subject line
  3. Best converting CTA in your email body

Besides producing better results (sales, conversions), higher engagement helps improve your future inboxing.

How to Setup an A/B or A/B/C Test on a Subject Line

Create your bulk/marketing campaign the same way you usually do, for example by copying and modifying your older campaign.

Determine how many variations do you want to test and click on the A/B Test button next to the subject line label:


AB testing is only available on bulk campaigns, not on transactional or automations. You can test up to 3 subject lines on a single campaign

TIP: You would need a good list size or high engagement to get statistically significant results.

A winner is selected at least 2 hours (or later) after campaign is sent, to allow for meaningful data collection, so you will only see raw data for the first 2 hours after a campaign is sent. 

AB test results

The winner is chosen based on open rate.

AB test results

That’s it. If you are a BigMailer customer you can reach out for assistance with this or anything else via chat 7 days a week.

If you want to AB test on send time, please refer to this article for detailed instructions.

Not a BigMailer customer? Why not try BigMailer for free, with no features locked? We are sure you will love it.