This is a question I am interested in. Potentially many people of unknown cleanliness have handled your mail's exterior, the food items at your local grocer, etc before they get to you. I am unclear on this thing's ability to live on surfaces, and also the shelf-life that it lives on those surfaces. For instance, maybe my mail was handled by a bunch of rando's but since 6 AM every day it's only been handled by my mailman, and then it sits in my box for a while til I grab it around 4:30. Feel like it's unlikely that even if my mailman coughed directly on my mail that morning, that it would still be sitting and waiting to infect me on my envelope 10+ hours later. But these are all guesses by me and I'd love to be informed if I am wrong, genuinely don't know.