Testcase preparation on-Project for Past due invoice email

Requirements :

1. Create a scheduled script to send a weekly email to the customers with terms.
2. The email will contain the past due invoices(due over 30 days) along with the interest of invoices.
3. Mail is sent only to the billing email id (custom column).
4. The customer email id is used as the recipient if there is no value in the billing email id.
5. All the invoices that are open and is overdue (over 30 days) will be fetched based on the due date field in the invoice.
6. If the due date field is empty, it will not be considered for email sending.
7. All the invoice of interest and interest finance charge invoices will be fetched and sent weekly to the customer.
8. Here will be sending a single email per customer in a week by attaching the invoices that are past due 30-60 days.
9. Only one email will be sent per customer, even if multiple invoices are past due 30-60 days in a week. So invoice numbers are not added in the subject line as it seems bulky if many invoices exist.
10. Also, the total amount due along with interest (The total amount due, including interest, is [Total amount due].) cannot be added to the email content since the interest of invoices is generated based on customer total overdue invoices and not based on each invoice.
11. So we suggest not including the amount in the email content. All open interest of invoices of the customer will be attached to every email because the interest of invoice may contain interest for multiple invoices.

The document is attached below for reference :