It turns out DMARC isn't actually required. Having it might help your acceptance score, but gmail and outlook don't actually require it. I know because I haven

It turns out DMARC isn't actually required. Having it might help your acceptance score, but gmail and outlook don't actually require it. I know because I haven't set up DMARC for my email domain, and my email still gets accepted by everyone. I believe it helps that I accept on TLS with a valid certificate, and I used Google's postmaster site verification.