Save draft and send message.
When you are all through editing a message, you send it with this
command. You can give a prefix argument ARG to monitor the first stage
of the delivery; this output can be found in a buffer called "*MH-E
The hook `mh-before-send-letter-hook' is run at the beginning of
this command. For example, if you want to check your spelling in
your message before sending, add the function `ispell-message'.
Unless `mh-insert-auto-fields' had previously been called
manually, the function `mh-insert-auto-fields' is called to
insert fields based upon the recipients. If fields are added, you
are given a chance to see and to confirm these fields before the
message is actually sent. You can do away with this confirmation
by turning off the option `mh-auto-fields-prompt-flag'.
In case the MH "send" program is installed under a different name,
use `mh-send-prog' to tell MH-E the name.
The hook `mh-annotate-msg-hook' is run after annotating the message and scan line. (fn &optional ARG)