What do you call private and public boxes where letters are put?
According to Cambridge dictionary, in US, a `mailbox` is a box outside a person's house where letters are put, but in UK, it's a box in the street or other public place in which you can put letters to be collected and sent. The dictionary states that `postbox` has the same meaning as the second meaning of mailbox (a public box) without mentioning US or UK usages. I could also find the word `letterbox` in the dictionary which seems to be used mostly in UK meaning both a `mail slot` and a postbox. According to the dictionary, *mail slot* is used in US to mean a rectangular hole in the door or in a wall near the entrance of a house or other building, through which letters, etc. are delivered. As a non-native speaker of English, I have these questions. **1.** Can I use *postbox* safely to mean a public box for letters in UK, US and Australia? **2.** What word(s) can be used in UK to mean the private box for letter outside your house? **3.** Is there any word/words that you can use to mean the private box for letter outside your house without ambiguity in UK, US and Australia? **4.** Can I also use *mail slot* in UK to mean *letterbox*? **5.** Do you have any other suggestions?