ˈmail slot noun [countableC] American EnglishAmE a letterbox 信箱；邮筒
mail slot• Barnabas dashed down the stairs and crouched by the mail slot, growling.• Those with goods stacked outside might leave a note asking you to slide money into the mail slot should you take anything.• Between late fall and early January, eight J.. Crew catalogs dropped through the mail slot of my front door.