Collection Process automation will send only one email to the customer which Ideally is logical but depending upon the Invoices it should also send all the invoice numbers along with the total amount Due.
Example:- We have customer X
Total invoice 3
Invoice 1 - ( Amount 100) ( Invoice number-1)
Invoice2- ( Amount 200) ( Invoice number-2)
Invoice 3-( Amount 300) ( Invoice number-3)

Now if we run collection process automation
The Criteria we have is that invoice should be send 3 days before invoice due date.
System should send email with Amount :- 600 and all the invoice numbers.

Through collection process automation we can send the invoices which are not due as well.