Need a windows powershell code to get a report of all delivered emails

I am trying to send reminder mails all customers with outstanding balance. To automate that I have created a powershell code which read email IDs and balance amounts from an excel and send email notifications to them. This is already achieved.

My next requirement is to include a code in that script or in any other way by which I get a report of which all mails are delivered to the recipient and then we can see which recipient has read their mail.