A lot of the time, good items placed on the curb have already been picked up by people on the street by the time that anyone on the list would see a "Curb Alert" email. As an alternative, how about announcing a day or two in advance of trash day that something good is going to go out, and if anyone wants it they can email back and come pick it up. If there's no response or the person doesn't show up, then it goes out as scheduled.