I know around here, if the box is not accessible, due to snow or it being knocked off by a plow (or pranksters), they are not required to deliver it.  When we had the dual blizzards in 2010, we boondock residents had to get our mail from the post office for more than a week b/c the boxes were blocked by gigantic mounds of plowed snow.  But yeah, Erika would know what the official rules are for delivery.

'And those seen dancing were thought to be insane by those who could not hear the musicNietzsche