I'm using mail to monitor unattended upgrades in Debian, and this helped me: How do you open mailx (aka mail) to read old mail when you have no new mail and view a list of old emails? - Super User https://superuser.com/questions/441871/how-do-you-open-mailx-to-read-old-mail-when-you-have-no-new-mail-and-view-a-list