Email and Invoice SettingsRecurring Invoices
Customize Overdue message Based on How Many Days have Passed
You can edit the Invoice Overdue Message on an email template and customize it. You can even change the message to say something different depending on how many days past due the invoice is. For example, you could fill in a message for the first  days, and that message would be for invoices 1-4 days overdue. Then you could fill in a Message for the next  days and that message would be for invoices 5-10 days overdue, etc.