Hello,
I had an error when the postfix server received an email :

postfix/pipe[1692]: 8699098029C:to=<xxxxxxx@xxxxxxxx.net>,relay=maildrop, delay=3100, delays=3100/0.02/0/0.04, dsn=4.3.0, status=deferred (temporary failure. Command output: /usr/local/bin/maildrop: Cannot have world/group permissions on the filter file - for your own good. )

Answer from Richard :

The rights should be:
-rw-------  vmail  wheel  /etc/maildroprc

and I complete :

Don't forget to restart services authdaemond, maildrop and postfix

Thank's Richard