Read Receipts

I have "read receipts" on all the mail I send out. I just like to know that the folks I'm sending mail to actually read the email. But I'm a little taken back when I get a receipt that says Not Read. Huh? No doubt these folks will be the people who later ask me about the thing I clearly detailed in the email!

"Oh, I'll just resend you the email."

Bwah.