[brightball]

Everything I have read to this point is that it will only affect you if you're sending > 5,000 message / day. Admittedly, there's no excuse for not having DMARC setup at that scale at this point as it's been a decade.

But as far as the policy, it doesn't have to be enforced. For most people, this just means that they'll need to a quick DNS entry to their domain for an unenforced policy.

Example...

TXT _dmarc.example.com "v=DMARC1; p=none;"

I did a 3 part DMARC writeup a while back if you're curious to learn more. It's not hard to setup. In fact, the smaller you are, the easier it is.

https://www.brightball.com/tag/dmarc-guide

[sbuk]

I'd add that DKIM is relitively simple to configue and, along with SPF, is a worthwhile endovour. It's considered as basic hygiene by spam filters.