Type: boolean
Default: yes
Controls whether or not Mutt makes the distinction between new messages and old unread messages. By default, Mutt will mark new messages as old if you exit a mailbox without reading them. The next time you start Mutt, the messages will show up with an "O" next to them in the index menu, indicating that they are old. In order to make Mutt treat all unread messages as new only, you can unset this variable.