Auto Invoice emailing and follow up if still unpaid after X days like Xero and QuickBooks has

Auto Invoice emailing and follow up if still unpaid after X days like Xero and QuickBooks has

We like how some software seems to automatically email customers invoices with a PAY NOW button for them to pay by Visa or Email money transfer - and we like how it seems to automatically email the invoice initially but also seems to follow up and send it again if it's unpaid still after X days - good functionality i think we all could use.