Editing Mailto:support@activecampaign.com (section)

=== Split Testing campaign type ===
The Split Testing campaign type allows you to send multiple versions of a campaign to portions of your list to determine which version generates more opens or clicks. The version of the campaign that performs the best, or the winner, can be sent to the remainder of your list.

When you set up sending, and you use the “Determine (and send using) the winner” option to calculate the winner, you can choose to send based on either:
* Best Click Rate
* Best Open Rate

For the “Determine (and send using) the winner by Best Open Rate,” any contacts using the Apple Mail app with MPP enabled will be excluded from the winner calculation.