Personally I hate "read receipts" and rarely ask for them when I send a message out. Because when I read a message, I don't always want to reply immediately, maybe it's late at night and I'm too tired to think straight, or I want to ponder the message a bit before answering. When I am forced to "OK" a read receipt, I feel under a lot of pressure to answer right away or risk offending the sender who sees that I read it but didn't respond. So I don't want to do that to other people. The only time I'll ask for one is if it's a time-sensitive message and I urgently need to contact the person in some way, so if they haven't read it for awhile I can contact them a different way.

I didn't know you could cancel a read receipt. It always forces me to hit "OK" before I can move on to another page.