1. Send statements on day 1 of the month to all customers. Include all invoices which are overdue between 0 to 300 days
2.Send statements on Monday every week to Customers categorised as "Cat1". Include invoices that are overdue by up to 300 days or due in the next 30 days
3. Send (daily) all invoices which has never been emailed to the customer and are due in 30 days
