How about a Firefox Addon to notify when emails are opened?

[macx]

I would think some smart computer geek (and I use that term as an accolade) could
come up with a Firefox Add-On that could automatically, or selectively as desired,
be embedded in or attached to emails irregardless of browser that would be activated
upon opening and send notification to the sender that it has been opened.

If legal constraints require, it could maybe ask for permission to send notification,
but that kind of nullifies lots of the reasons for something like that in the first place.