Add a payment reminder
On your SumUp profile, click "Invoices".
Tap "New Invoice" and create an invoice.
On the screen with the option to add recipients and a message, check the reminder box.
Customers will be reminded of unpaid invoices the day after the payment deadline and further reminders three and seven days after the deadline.
Once sent, reminders cannot be cancelled. However, they'll only be sent if the invoice hasn’t been paid in full by its due date
You can also create and send payment reminders for unpaid invoices after you've sent them.