A/B testing is a feature that enables you to try a couple of options with samples of your database, see the results and then send the best option to the rest of the database.
Options that you can try are content, subject line and email pre-header.
With A/B Testing you have 3 message sections. Message, Message A and Message B.
The Message section is where you can create a "Master" Message. You can then copy and edit this with the relevant changes for each of the Message A and Message B sections. This enables you to quickly create the A and B messages without having to rebuild everything from scratch.
Once you’ve created your A and B messages, you need to upload your full list of recipients and select how many are to receive Message A and how many Message B.
As the results come in for the Message A and Message B messages, they will be displayed in the "Compare Results" section. Here you can see the delivery, Opens and Click results for the 2 messages. Use the "Refresh" button to update the results as they come in.
From the results you can then choose to send the message with the best results to either all remaining recipients, or all remaining recipients and the recipients of the other message. You can also choose to do the selection manually, or do it based on delivery and tracking results after a set time.