nixy

nix·ie also nix·y
n. Slang pl. nix·ies

A misaddressed or illegibly addressed piece of mail, therefore undeliverable.

Make sure you put a return address, lest it ends up in the nixy netherregions!
No, it never got to Grandpa. For all we know, it's a NIXY.
If only his handwriting had been slightly better, the love letter would never have ended up a nixy, and the two might have ended up together. Ah the cruel cruel fates!
I see snowflakes as... God's nixies.
Trixie may be sexy as a pixie, but she's notorious for writing nixies.