If I enable postscreen on a Debian-Host I’ll get this strange message in my mail.log:
Feb 13 08:38:37 tardis postfix/postscreen[17453]: close database /var/lib/postfix/postscreen_cache.db: No such file or directory (possible Berkeley DB bug)
It looks like the postscreen_cache.db-file is located in /var/lib/postfix instead of the postfix-jail /var/spool/postfix/var/lib/postfix. So we can fix it by moving the file into the jail:
root@tardis:~# service postfix stop
root@tardis:~# mkdir -p /var/spool/postfix/var/lib/postfix
root@tardis:~# mv /var/lib/postfix/postscreen_cache.db /var/spool/postfix/var/lib/postfix
root@tardis:~# ln -s /var/spool/postfix/var/lib/postfix/postscreen_cache.db /var/lib/postfix/postscreen_cache.db
root@tardis:~# service postfix start