Did the same. From Qmail/Courier to now using Postfix/Dovecot. But am not using Spamassassin. Instead, filter all TLDs except those that I white listed. Then by

Did the same. From Qmail/Courier to now using Postfix/Dovecot. But am not using Spamassassin. Instead, filter all TLDs except those that I white listed. Then by reverse ip, dmarc and sfp check. And lastly block domains from which I have received a new mail and marked it as spam from the client side within 24 hours.