http://www.fmi.uni-passau.de/archive/doc/unix/unixhelp/Unixhelp/mail_six.3.1.html (Einblicke ins Internet, 10/1995)To reply only to the person who originally sent you the mail message, use the command:
R message list
You would use this command where the mail message had been carbon copied to several other people, but you only wanted the original sender to see your reply.