DNS MX/SPF/DMARC records without actuall emails on domain

I created website for someone, but also someone (I guess some SEO guy) told this person that I made big mistake because there are missing DNS records on domain (mx, SPF, dmarc). Now I need to "fix" my error.

Thing is, of course these records are used for Email purposes, but there is NO email in this domain (just simple free Gmail account).

So, is there any reason to add these records anyway? How they should look like? Only reason I can think of is preventing SPAM using my domain identity. But I thought that SPAM filters are not going to pass email from my domain anyway if these records are missing, so what's the point?

Solution 1:

The point would largely boil down to being a good citizen and reducing abuse, like making your domain less useful for spammers to impersonate and to make it immediately clear to others that mail is not deliverable there.

If the claim is accurate that the domain is not used for either sending or receiving email at all, you could add something like this:

domain.example. IN MX 0 .
domain.example. IN TXT "v=spf1 -all"
_dmarc.domain.example. IN TXT "v=DMARC1; p=reject; aspf=s; adkim=s;"

This indicates that inbound mail is not accepted (null MX), and that any mail sent from the domain should be rejected (SPF policy that lists no allowed senders + DMARC policy enforces From-header alignment).

Solution 2:

If you're not serving email, and you're not planning to send an email out from the domain, then you are correct - you do not need these records.

EDIT: The other answer indicating utilization of records to zero out possibility of bad actors using the domain instead is a much more thought-out answer and should be considered best practice. I know I'm going to do so now!