set display-outgoing-message

SET DISPLAY-OUTGOING-MESSAGE NO/yes  -  whether to show message text

With the usual NO setting, in any situation where you enter "text mode"
  any existing text is not redisplayed.  (You can redisplay the existing 
  text by typing control-k or control-l.)

If you change it to YES, you will see the existing text, with the cursor
  at a new line right after it.  If the text is too long to fit on screen,
  you will see the last screenful of it.  

There might be existing text to be displayed:
o  If, at the Send> prompt, you use the TEXT command to go back and add
   more text.
o  If you used the option INCLUDING with a REPLY command (the included
   text is part of the reply message).

For more help, type "help" and one of the following:
(at any prompt:)  save-init   set   show  
                  text-mode    set reply-initial-display
(at the MM> or Read> prompts:)  reply   send
(at the Send> prompt:)  text