Receipt requested

You know the email option that notifies you when someone opens the email you sent? Almost everyone I know in the office turns it off, as it's annoying to constantly have your inbox flooded with "receipts." So when someone still has it on, and sends me a personal email, I feel as if I'm being monitored. Am I being evaluated on whether I'm sitting there, waiting for his email to pop up? Is he watching how quickly I respond after reading?