Is there a way of knowing if an email that you sent has be read/opened by the recipient?

I have wondered the same thing. There are times when I have time to read an email... But not enough time to answer it as deeply as I would want so I wait til I can respond. I hope no one has ever thought "I pour my guts out and she doesn't even respond!?!?" 🙂

I am pretty sure there is a software program out there for it. I don't know if it is available to the general public.  I remember way back when the agency I worked for had that feature on their mail system.