郵便 ゆうびん受箱 うけばこじゃありませんでした
yūbin'ukebakojārimasendeshita

Noun
Desu Copula

The polite, past negative form of 郵便受箱

1. It wasn't a mailbox.; It was not a mailbox.

Past/Perfective
Negative
Polite
Terminal Form