This file is hardlinked at each of these locations: /etc/dovecot/private/README /etc/dovecot/README.private /etc/postfix/private/README /etc/postfix/README.private The "private" subdirectory under each of /etc/dovecot and /etc/postfix has been secured to protect access to the SQLite mail database. Each private directory is mode 750, and owned by root:X, where X is dovecot and postfix respectively. The database itself is world readable, but non-root users other than dovecot and postfix will be unable to get to it.