Hi,
For system emails, it says this:
Abandoned Cart An action email will be generated within 24 hours of a customer abandoning their shopping cart, which will be sent automatically on a specified number of days after the cart was abandoned. You’re able to set the number of days between the cart being abandoned and the day the action email is sent to the customer.
Please Note: Only abandoned carts where a customer entered their email address before abandoning their cart will apply.
Action Emails / Abandoned Cart
If a card declines, is that abandoned? Or just people that never try payment and did put in their email address.