[dangrossman]

I have no idea (didn't find out from a quick browse through the site), but the first thing that came to mind was an image in the mail, pointing to a server that slowly trickles a response without ever finishing so it can measure how long the other end is listening.

[barumrho]

I guess that could work if mail clients don't have timeouts for images.

I still can't imagine how they would detect deletion though.

[dangrossman]

They're just calling "viewed for <x seconds" a deletion, it seems...

[wlievens]

A timeout would possibly be after an engagement time that means "probably read the whole thing", e.g. 60 seconds.

[tlack]

Pretty genius idea but easy to replicate by the big boys..

[OJKoukaz]

Big boys move slowly. Plus, what isn't "easy to replicate?" aside from network effects.

[MrEnigma]

I worked at an ESP (Email Service Provider) a few years back. It may not be anymore, but it was a crazy environment back then of everyone trying to compete.

The major issue with this is going to be scaling it, with large ESP's doing 50-100 million messages a day, and 20-30% of those being opened, that's a lot of processes. This solution will probably be effective, mostly because it's going to a much smaller segment.