Variable: message-send-hook
message-send-hook is a customizable variable defined in message.el.gz.
Value
nil
Documentation
Hook run before sending messages.
This hook is run quite early when sending.
Probably introduced at or before Emacs version 27.1.
Source Code
;; Defined in /usr/src/emacs/lisp/gnus/message.el.gz
(defcustom message-send-hook nil
"Hook run before sending messages.
This hook is run quite early when sending."
:group 'message-various
:options '(ispell-message)
:link '(custom-manual "(message)Various Message Variables")
:type 'hook)