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
