Use /etc/rc.conf.d/postfix to override the defaults:

Martti


# cat /etc/rc.conf.d/postfix

required_files='/usr/pkg/etc/postfix/main.cf'
start_cmd='/usr/pkg/sbin/postfix start'
stop_cmd='/usr/pkg/sbin/postfix stop'
reload_cmd='/usr/pkg/sbin/postfix reload'