My husband traveled with his job for 6 yrs and we did 1 assignment in Deming NM. It's 30 miles from old Mexico border and slap dab in the middle of the desert. We didn't get mail one time for 3 days because of dirt storms. Literally couldn't see your hand in front of your face. You turn the car AC on it blew dirt in your face. So I know dirt can absolutely stop mail delivery so I bet snow could to. We went camping in Estes Park CO one summer and they told us people in the mts have to come down on their snow mobiles to pick up their mail. YUK