mailbag

2. A collection of letters and questions sent to a newspaper, magazine, or radio show, often answered in a special section.

The magazine's mailbag this week is full of readers' questions about gardening.

3. A bag used to hold mail on a train, ship, or plane.

Workers loaded the mailbag onto the train before it departed.

4. A large bag for storing or transporting letters in an office or post office.

She sorted the envelopes into the mailbag for the morning pickup.