From Elendor
There are many commands that allow you to edit all aspects of your message
before you send it. To send it, see HELP mail sending.
See HELP +edit for editing the text of a message.
See HELP +undo for undoing inadvertent changes.
See HELP +address for changing the address of a message.
See HELP +subject to change the subject line of a message.
See HELP +cc to add/remove people to/from a message's address.
See HELP +include to insert the text of some other message.
See HELP +erase to erase the text of a message in progress.
See HELP +proof to read over a message in progress.
See HELP +draft to read a message and see all the hidden codes too.
If you use Pueblo or Smial as your client program (see NEWS SMIAL) then you
can use the +PPROOF command to edit mail messages using a graphical
interface. See HELP +pproof for details.