Read Receipt for Emails

When an order is placed an email is generated. We've had an issue with our cart. The employee who was to be managing it routed all the mails to their junk. What we need to be able to request a read receipt for each email that is sent so that we know it was opened. I know that this can be done by adding a line or two to the file that sends the email. What I need to know is where in Zen Cart to put it.

Once it's done, I'm quite happy to offer it as a contribution.

As I uinderstand it, most newer email clients are set up to prevent this very thing, because of spammers. I doubt if it would work in the majority of cases.

While this might not work in most cases, it should in this one since everything is internal. Web server, mail server, desktops, etc. What I need is to be able to prove that the employee in question is getting the emails and not processing them.

Assuming you have control of the mail server, I would set up a forwarder to this employee's address and also to another address that you control and direct the Zencart emails to the forwarding address. That way, all emails would go to both addresses and it should be simple to show that he received them.