xlbiff | X Literate Biff. Displays From and Subject lines of your new mail | Mehr ...
Xlbiff lurks in the background, monitoring your mailbox file (normally /var/spool/mail/). When something shows up there, it invokes the MH scan(1) command and displays the output in a window. If more mail comes in, it scans again and resizes accordingly. . Clicking the left mouse button anywhere in the window causes it to vanish. It will also vanish if you inc(1) and the mailbox becomes empty. Xlbiff is modeled after xconsole -- its job is to sit invisibly and pop up only when something demands your attention.
