set escape-automatic-send

SET ESCAPE-AUTOMATIC-SEND NO/yes  -  whether to send automatically

With the usual NO setting, outgoing messages are not sent when you use
  the ESCAPE key to finish typing them; instead, you see the Send> prompt 
  and can choose whether to send or quit.  

If you change it to YES, then if you use the ESCAPE key to indicate the 
  end of your message, it will be sent immediately.  This saves you one 
  command, but also makes it possible for you to send accidentally.

For more help, type "help" and one of the following:
(at any prompt:)  save-init   set   show   set control-d-automatic-send
(at the MM> or Read> prompt:)  send
(at the Send> prompt:)  send