So where did my lost piece of mail most likely go?

Just send a letter to:

Santa Claus
North Pole
Canada
H0H 0H0
Probably, though, if you mail now, you’ll get a letter back after Christmas, gently suggesting you write earlier next year.

Various postal administrations around the world provide a Santa service.

In Australia, you can send a letter to Santa, North Pole 9999 with a standard stamp and you will get a reply from the bearded guy.

I suspect most letters “Santa” gets are pranks. I sent one on behalf of my boss one year.

My letter carrier husband says he knows this as a postal shorthand for requiring a better address (if I understood his explanation right).

The weird thing is that the Post Office had delivered something to that same address before. With the same error.