If they already have the speed camera installed (assuming they did... thats how they got the before figure), then I would think the mailing the ticket part already exists.
I know all the red-light cameras (close enough) in Toronto get the tickets mailed out. You can even pay them online now!
I would have to assume that this absolutely is the case. As far as I can figure, there'd be no way to get percentage decrease in speeding without already having a speed camera installed as a baseline. Without a speed camera, the only way to measure speeding is by number of tickets issued by police at that exact intersection. But police would only ever be able to catch a small percentage of all speeders, whereas speed cameras could potentially catch all speeders. So installing a speed camera would likely show an increase in the number of speeding tickets issued, whether or not the actual number of speeders changed.
In fact, a cursory googling turns up no studies showing whether speed cameras actually decrease the number of speeders. Only inference can be made, as studies DO show that speed cameras decrease the number of injuries and deaths.
The best way to measure the effect of speed cameras on speeding to have some hidden cameras monitoring the section of road, recording speeds. Motorists should not be able to see them. Then collect some baseline data. Then install the speed camera. Collect more data (from the original camera). Compare the two.
Same in my city of Chicago ... but in this example it's just more marked and apparent that you'll get a fine (i.e. directly in the middle of the intersection showing your speed). If there was already a speed camera installed, it probably would be indicated by some average looking sign a mile back.
I know all the red-light cameras (close enough) in Toronto get the tickets mailed out. You can even pay them online now!