There is a difference between knowing that the message arrived in the recipient's inbox, and knowing that the recipient has opened the message. See http://en.wi

There is a difference between knowing that the message arrived in the recipient's inbox, and knowing that the recipient has opened the message. See http://en.wikipedia.org/wiki/Return_receipt#E-mail http://en.wikipedia.org/wiki/Return_receipt#E-mail (DSN versus MDN). MDNs are not a very good idea, but widespread use of DSNs would probably be nice. There are quite a lot of cases where you just have to know if your message arrived, but it is tedious (and slightly rude) to ask for confirmation.