Recently there was a discussion about file permissions and ownership. My postfix setup is as far as I know fairly conventional Debian stretch.
/etc/postfix root root 755 Main.cf root root 644 Master.cf root root 644 /etc/postfix/maps root root 755 Map, pcre etc root root 644 /etc/postfix/sasl root root 755 -- /etc/postfix/sql root root 755 sql ? ? 644 Would I be better with directories as 750 and files as 640. Ownership = postfix in all cases.
