投信口 meaning in English

letter drop

Postal services - apertures of private letter boxes and letter plates - requirements and test methods
邮政业务.私人信箱投信口和街门前投信栏板.要求和试验方法
Postal services - apertures of private letter boxes and letter plates - requirements and test methods
邮政服务业务.私人信箱和信箱投信口金属板缝隙.要求和试验方法
I even paused briefly with the letter part way into the mail slot before i thrust the letter into the mailbox
甚至在信已经部分插入投信口时，还犹豫了一会儿才把它推进邮筒。
Postal services - apertures of private letter boxes and letter plates - requirements and test methods ; german version en 13724 : 2002
邮政业务.私人信箱和信箱投信口金属板缝隙要求和试验