noun
Refers to a physical box for receiving mail, such as a home mailbox or a public post box.
新しい家の郵便受け箱は赤いです。
The mailbox at the new house is red.
郵便受け箱に手紙が届いていた。
A letter had arrived in the mailbox.
Compound of 郵便 (mail) + 受け (receiving) + 箱 (box).