Translation guide
A letter box is a container for receiving incoming mail, typically at a home or office. In Japanese, the most common term is 郵便受け (yūbin'uke), but other words exist depending on context, such as public postboxes or slots in doors.
A box or slot for receiving delivered mail at a residence or office.
The standard term for a mailbox attached to a house or building where mail is delivered.
Please check the letter box.
Commonly used for both home mailboxes and public postboxes. Context usually clarifies which is meant.
Less common; can refer to a mailbox but often sounds slightly more formal or old-fashioned.
A red or blue box on the street where you deposit outgoing mail.
A slot in a door or wall for mail delivery, common in apartments.
郵便受け (yūbin'uke) is specifically for receiving mail at a residence. ポスト (posuto) can mean either a home mailbox or a public postbox, but context usually makes it clear. When in doubt, use 郵便受け for your own mailbox and ポスト for the red box on the street.
I installed a new letter box.
There was a letter in the letter box.
Open the letter box.
More explicit than ポスト, emphasizing it's for mail. Used when distinction is needed.
Where is the letter box?