Oh boy. I just set up my company a few months back, unfortunately I never had to go into email too much, so I didn't set up DKIM/SPF/DMARC. Then I started receiving emails from my own domain, I panicked because spoooofingg (read with spooky voice) and set up all three. I was bashed for an entire week with reports from all major email services with DMARC reports.

Fortunately I still only have a couple clients so no one was the wiser.

UPDATE: It ended up in a simple scare, nothing was affected and I'm not in any list that I know of, in case you're wondering