The phenomenon I believe you're talking about is called "return receipts" and while there are certainly some Mac email programs that support them, they generally don't work outside of the same network. Why? Well, for one thing, if you send an email with a return receipt requested to a person who's email program *doesn't* support return receipts, you never get notified that they read the email. Also, there's plenty of security concern here - imagine things from the receiver's point of view, do I really want my email program sending info about when I read what to whoever sent me the email? For this reason I believe many ISPs and network admins block or otherwise prevent "return receipts" from working.
Return receipts might work in closed networks (like within a school or a company) where everybody is required to use the same software with the same set-up, but it generally just doensn't work outside that.
Now your dad may be using a spammer's tool of some sort (which seems unlikely because he'd need to host images somewhere and have all kinds of script things set up, but who knows?) in which case the return receipt request is replaced by a tiny unique image reference that notifies the sender when that image is downloaded from a web server somewhere - but this too often doesn't work (like if your mail program doesn't support HTML mail, or if you turn off images).
Regardless, you (and your dad) should realize that return receipts are, at best, flaky and unreliable, and at worst obnoxious and a violation of privacy/security concerns.
In short, don't do that.
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