mh-modify
mh-modify is an interactive autoloaded compiled Lisp function in `mh-folder.el
'.
(mh-modify &optional MESSAGE)
Edit message.
There are times when you need to edit a message. For example, you
may need to fix a broken Content-Type header field. You can do
this with this command. It displays the raw message in an
editable buffer. When you are done editing, save and kill the
buffer as you would any other.
From a program, edit MESSAGE; nil means edit current message.