To configure Postfix for local delivery, run the following commands:

export KEYTRUSTEE_SERVER_PK="/var/lib/keytrustee/.keytrustee/.ssl/ssl-cert-keytrustee-pk.pem"
export KEYTRUSTEE_SERVER_CERT="/var/lib/keytrustee/.keytrustee/.ssl/ssl-cert-keytrustee.pem"
export KEYTRUSTEE_SERVER_CA="/var/lib/keytrustee/.keytrustee/.ssl/ssl-cert-keytrustee-ca.pem"
export KEYTRUSTEE_SERVER_HOSTNAME="$(hostname -f)"  # or adjust as required
postconf -e 'mailbox_command ='
postconf -e 'smtpd_sasl_local_domain ='
postconf -e 'smtpd_sasl_auth_enable = yes'
postconf -e 'smtpd_sasl_security_options = noanonymous'
postconf -e 'broken_sasl_auth_clients = yes'
postconf -e 'smtpd_recipient_restrictions = permit_sasl_authenticated,permit_mynetworks,reject_unauth_destination'
postconf -e 'inet_interfaces = localhost'
postconf -e 'smtp_tls_security_level = may'
postconf -e 'smtpd_tls_security_level = may'

Start the Postfix service and ensure that it starts at boot:

service postfix restart
sudo chkconfig --level 235 postfix on