SPF, DKIM and DMARC? I jumped down the rabbit hole and set up my own mail server about a year ago. With postfix configured to look at the above I get zero spam

SPF, DKIM and DMARC? I jumped down the rabbit hole and set up my own mail server about a year ago. With postfix configured to look at the above I get zero spam. Looking at logs, I do get lots of connection attempts from random IPs in China and such, but my postfix unilaterally rejects anyone that doesn't have good DNS settings.