By default all transactions you make with your Pliant cards require a receipt. Transactions missing a receipt are marked with a missing receipt icon in the "Transactions" page. A filter at the top of the "Transactions" page includes the count of transactions missing a receipt. Clicking the filter displays all transactions that require a receipt.
Every Thursday we send a reminder email with the number of transactions that are still missing a receipt. If you would like to pause these emails, you can turn off the corresponding toggle in "Profile Details" -> "Manage notifications".