迷子まいご郵ゆう便びん

noun

lost mail; undeliverable mail

Mail that cannot be delivered to the intended recipient, often due to an incorrect or incomplete address.

• 住じゅう所しょが間ま違ちがっていたため、迷子まいご郵ゆう便びんになってしまった。

  Because the address was wrong, it became undeliverable mail.