IPA: /ˈmeɪlˌruːm/
KK: /ˈmeɪlˌrum/
A space in a building where letters and packages are received, sorted, and sent out for a business or organization.
The mailroom is busy every morning as employees sort through the incoming packages.
Mailroom → The word is formed from "mail" (from Old French *male*, meaning a bag or pouch) and "room" (from Old English *rum*, meaning space or area). A mailroom is a designated space for handling mail, typically in an office or building.
Think of a 'bag' ('mail') where letters and packages are kept in a 'space' ('room') — that's what a mailroom is.
No commonly confused words.