message-archive-note
message-archive-note is a variable defined in `message.el
'.
Its value is "X-No-Archive: Yes - save http://groups.google.com/"Documentation: Note to insert why you wouldn't want this posting archived. If nil, don't insert any text in the body. You can customize this variable. This variable was introduced, or its default value was changed, in version 22.1 of Emacs.