On Tue, 15 May 2012, Stan Hoeppner writes

This "unsend" feature was created to protect idiots from themselves, nothing more. Which is why the IETF draft went nowhere.

You can only "fix" some types of human stupidity with software. This is not one of them.

I thought someone could make money coming up with an "unsend" and "untwitter" service that all it does is to queue the outgoing message for 5 minutes, during which the sender can re-consider and remove it from the queue. Sorot of like the kill-switch for live broadcasts. But as the saying goes, you can't make things foolproof, as they keep making better fools.

As to the OP trying to determine whether an Email message has been read, an indirect and imperfect technique, used by spammers and marketing critters, is to web bug

http://en.wikipedia.org/wiki/Web_bugs

It works by placing innocuous individualized tags in HTML formatted Email e.g. "http://your.domain/?id={hash}>" that downloads a 1x1 dot). You can then correlate web logs with the hashes to see which messages got rendered. A hit does not necessarily mean it got read, and the absense does not mean it was ignored, but it's better than nothing. If you value your privacy, turn off HTML rendering on your Email reader.

Joseph Tam jtam.home@gmail.com