This is something I'm looking at getting into 7.2. The big roadblock currently is trying to figure out a trigger. We abandoned actual cron jobs for version 7 since many people don't have the option to run them on their server. So, I need to figure out something to trigger it and make sure it only gets run once per day.
I have a few ideas in mind, but trying to come up with something with the least amount of impact on overall speed, since we don't want to have to check if they've been sent that day on every page load.
