Editing a message
You can enter the vi editor
by typing ~v on a new line while creating a
message, or by entering the v command at the
mail prompt.
Use the VISUAL environment variable to select an
editor other than vi.
Similarly, you can enter the editor selected using
the EDITOR environment variable
by typing ~e on a new line while creating a
message.
For details on how to set environment variables, see ``Setting environment variables'' in the Operating System User's Guide.