# postconf -n
config_directory = /etc/postfix
disable_dns_lookups = yes
inet_interfaces = $myhostname, localhost
mailbox_command = /usr/bin/procmail -a $DOMAIN -d $LOGNAME
mydestination = $myhostname, localhost
mydomain = lin
myhostname = mail.lin
mynetworks = 168.100.100.140/24, 127.0.0.0/8
mynetworks_style = host
myorigin = $myhostname
relay_domains = $mydestination
smtpd_etrn_restrictions = permit_mynetworks, reject
smtpd_helo_required = yes
smtpd_recipient_restrictions = check_recipient_access cdb:/etc/postfix/validdomain, reject_unauth_destination
unknown_local_recipient_reject_code = 550