biff - 1:0.17.pre20000412-5.1 main

biff is a small program that prints a message to your terminal
when new email arrives. Actually, the message is printed by
the comsat daemon, and biff just enables/disables the u+x
permission flag for the terminal, which comsat uses to determine
whether or not to write to your terminal.
.
biff is mainly of historic interest, since there are much better
alternatives (such as xlbiff and gbuffy) that are network-aware and
do not require a daemon. Although there are no known security
problems, running additional services is often considered risky.
.
By default, the biff service is disabled. To use biff email
notification, you must enable this service by running 'update-inetd
--enable biff' after the package is installed. You may also need
to modify the configuration of your mail transport agent to enable
comsat notification.