reply

REPLY  -   write and send a reply to the current message

Usage:  REPLY [option1] [option2]

  Unless specified, the options "sender not-including" are assumed.
  The options are: 
      sender: send the reply only to the sender. 
      all: send the reply to everyone in the TO and CC fields.  
  and also:
      including: include the original message in the reply.
      not-including: send just the reply.

The REPLY command sends a reply.  It is similar to SEND, but the TO field
  is supplied from the FROM of the original; the SUBJECT field is copied;
  and a CC field may appear if you specify "all".  You then just type
  the text as in SENDing.  Your message will have an IN-REPLY-TO field 
  showing the date of the original message you received.

The default "sender not-including" is controlled by two variables,
  SET REPLY-ALL NO and SET REPLY-INSERT NO.  Change them to make "all"
  or "including" the usual option.
  
Examples showing use of the options:
    Read>reply	 			= reply sender not-including	
    Read>reply all			= reply all not-including
    Read>reply including		= reply sender including
    Read>reply all including    	

The command SET REPLY-INITIAL-DISPLAY YES will let you see the header fields
  created by REPLY, and the included original message when you use the
  "including" option.

The command SET REPLY-INDENT defines the characters used to set off
  the original message when "reply including" is used.  The usual indent
  is > and a space ("> ").

For more help type "help" and one of these topics:
  send   addressing   message-handling   text-mode

For help about customizing REPLY, type "help set" and one of these topics:
  reply-all   reply-include-me   reply-indent   reply-initial-display