De acordo com a página mail(1)
man, list
está funcionando bem:
list (l) List the valid mail commands.
O que você está procurando é provavelmente h
ou z
headers
(h) Lists the current windowful of headers. To view the
next or previous group of headers, see the z command.
z mail presents message headers in windowfuls as described under
the headers command. You can move mail's attention forward to
the next window with the z command. Also, you can move to the
previous window by using z-.