SET REPLY-INCLUDE-ME NO/yes  -  whether the "all" option includes me

With the usual NO setting, when you REPLY with the "all" option, MM does
  not send a copy of the reply back to you, even though you may be in 
  the TO or CC field of the original message.  

If you change it to YES, the "all" option will include you in the mailing
  if your address is in the TO or CC field of the original.

(This variable is not used to send yourself copies of all your mail.  See
  SET DEFAULT-CC-LIST and DEFAULT-BCC-LIST to include your own address
  in all outgoing mail.  See also SET SAVED-MESSAGES-FILE.)

For more help, type "help" and one of the following:
(at any prompt:)  save-init   set   show   set reply-all
                  set default-bcc-list   set default-cc-list   
                  set saved-messages-file
(at the MM> or Read> prompts:)  reply   reply-insert
