Editing Mailto:support@activecampaign.com (section)

=== The "Resend a campaign" feature ===
The "Resend a campaign" feature lets you resend your campaign in the following ways:
* Create a new campaign based on this campaign
* Send to new contacts since the email was originally sent
* Send to contacts who have not read/opened this campaign

For the "Send to contacts who have not read/opened this campaign" option, any contacts using the Apple Mail app with MPP enabled will be excluded from the campaign resend.