Grade your domain
Enter a domain and get a letter grade for its email security — SPF, DKIM, DMARC, MX and MTA-STS — plus an ordered list of exactly what to fix, biggest gap first. Everything is a public DNS read: nothing is written, no mail is sent.
We ran it on our own domain first. It scored 48 / D — it published no apex SPF record. Publishing one moved it to 69 / C the same afternoon. This is that check.