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.