[noun] [C] - a large strong bag used by the post office for transporting and carrying letters and parcelsA person's or organization's mailbag (UK postbag) is all the letters they receive at one time or on one subject.Since the controversial programme was broadcast, the BBC's mailbag has been bulging.
MAILBAG
Meaning of MAILBAG in English
Cambridge English vocab. Кембриджский английский словарь. 2012