postbag
noun UK uk/ˈpəʊst.bæɡ/ us/ˈpoʊst.bæɡ/ (UK also and US mailbag)
[ U ]一次发送（或收进）的信件;（有关同一主题的）一批信件
the number of letters received at one time or on one subject
It was clear from our postbag that viewers were unhappy about the programme. 从我们收到的来信可以清楚看出，观众们对这个节目不满意。
[ C ]邮袋
a large strong bag used by the Post Office for transporting and carrying letters and parcels