readers' column; letters to the editor section
Refers to the section in a newspaper or magazine where letters from readers are published.
His opinion appeared in the readers' column.
Reading the letters to the editor section of the newspaper is my daily routine.
投書欄 traditionally refers to a newspaper section for readers' letters and complaints, while 投稿欄 is the broader modern term covering any reader-submitted content, print or online.
Compound of 投書 (tōsho, 'letter to the editor') + 欄 (ran, 'column').