Not Snow Nor Rain

Sam should have let the 22 nixies go to the dead letter office ... or gone there himself for sanctuary!
On his first day as a mail carrier, Sam Wilson noted that inscription, cribbed from Herodotus, on the General Post Office, and took it to heart: Not snow, nor rain, nor heat, nor gloom of night stays these couriers from the swift completion of their appointed rounds.
It couldn't be literally true, of course. Given a real blizzard, it would be impossible to make his way through the pathless drifts; and if there had been a major flood, he could hardly have swum to deliver letters to the marooned. Moreover, if he couldn't find the addressee, there was nothing to do but mark the envelope Not known at this address, and take it back to be returned to the addresser or consigned to the Dead Letter Office. But through the years, Sam Wilson had been as consciously faithful and efficient as any Persian messenger.
Now the long years had galloped by, and this was the very last time he would walk his route before his retirement.
It would be good to put his feet up somewhere and ease them back into comfort; they had been Sam's loyal servants and they were more worn out than he was. But the thought of retirement bothered him. Mollie was going to get sick of having him around the house all day, and he was damned if he was going to sit on a park bench like other discarded old men and suck a pipe and stare at nothing, waiting for the hours to pass in a vacuum. He had his big interest, of course—his status as a devoted science fiction fan; he would have time now to read and reread, to watch hopefully from the roof of his apartment house for signs of a flying saucer. But that wasn't enough; what he needed was a project to keep him alert and occupied.
On his last delivery he found it.
The Ochterlonie Building, way down on lower Second Avenue, was a rundown, shabby old firetrap, once as solid as the Scotsman who had built it and named it for himself, but now, with its single open-cage elevator and its sagging floors, attracting only quack doctors and dubious private eyes and similar fauna on the edge of free enterprise. Sam had been delivering to it now for 35 years, watching its slow deterioration.