[MovedGoalPosts]

Actually a read receipt doesn't alway mean that it's been read, it could just have been received by the server, but then other processes knocked it into spam or whatever. It's why I suspect many firms now refuse to accept formal notices by email.

I recently found a misconfiguration on my office's exchange server. If a distribution group was set up, say sales@company so that mails to that address were then autoforwarded to all the email users in the sales team, by default it appears that the distribution group was sending a read receipt. Yet nobody at that point would have seen it, and spam or junk filters could have taken it away. I've fixed that error now, but as it was a default setting, working the opposite way that people might have expected to not send out a read receipt, I do wonder how many other servers are wrongly configured.