[now rare] To notify someone of incoming mail. From the BSD utility
biff(1), which was in turn named after a friendly dog who used to
chase frisbees in the halls at UCB while 4.2BSD was in development.
There was a legend that it had a habit of barking whenever the
mailman came, but the author of biff says this is not true. No
relation to {B1FF}.
[glossary]