I would have thought someone in that target audience is potentially going to be infected just because of the size of the mail drop. Potential infection period on paper is currently quoted at up to 3 hours, I believe.
I dont deal with my mail for 3 days i have a litter picker so i pick it up move that days mail to one side and just leave it in the hallway. Anything that wont fit in the letterbox the postman rings the door bell and leaves it on the doorstep then same procedure i am now on day 22 of isolation and expect to be so for at least 4 months but hey it's only 271 days to Christmas.