Instalação dos pacotes:
apt-get install postfix-policyd-spf-perl libmail-spf-perl
Adicione no arquivo main.cf do /etc/postfix
spf-policyd_time_limit = 3600s smtpd_recipient_restrictions = ... check_policy_service unix:private/policy-spf, ...
Adicione no arquivo master.cf do /etc/postfix
policy-spf unix - n n - - spawn user=nobody argv=/usr/sbin/postfix-policyd-spf-perl
Reinicialize o postfix
/etc/init.d/postfix reload
Verifique a funcionalidade
tail -f /var/log/mail.log
