fix(mu4e): Configure msmtp to preserve email body content

The mu4e msmtp configuration was causing email bodies to be stripped,
especially for multipart messages from org-msg. This was due to missing
critical msmtp settings.

Changes:
- Add message-sendmail-f-is-evil to prevent -f flag issues
- Add --read-envelope-from to msmtp arguments
- Set both send-mail-function and message-send-mail-function

Fixes: nixos-configs-9l8

home/roles/emacs/doom/config.el

@@ -211,11 +211,16 @@
         mu4e-headers-time-format "%H:%M")
 
   ;; Sending mail via msmtp
-  (setq message-send-mail-function 'message-send-mail-with-sendmail
+  ;; NOTE: message-sendmail-f-is-evil and --read-envelope-from are required
-        sendmail-program (executable-find "msmtp")
+  ;; to prevent msmtp from stripping the email body when processing headers.
-        message-sendmail-envelope-from 'header
+  ;; Without these, multipart messages (especially from org-msg) may arrive
-        mail-envelope-from 'header
+  ;; with empty bodies.
-        mail-specify-envelope-from t))
+  (setq sendmail-program (executable-find "msmtp")
+        send-mail-function #'message-send-mail-with-sendmail
+        message-send-mail-function #'message-send-mail-with-sendmail
+        message-sendmail-f-is-evil t
+        message-sendmail-extra-arguments '("--read-envelope-from")
+        message-sendmail-envelope-from 'header))
 
 ;; Whenever you reconfigure a package, make sure to wrap your config in an
 ;; `after!' block, otherwise Doom's defaults may override your settings. E.g.