Check SPF, DKIM and DMARC for any domain.
Type a domain and see whether its email authentication is set up correctly. No sign-in, nothing to install, and no access to anything of yours.
What this checks
- SPF.Whether the domain says who is allowed to send as it, and whether the record is valid — one record, under ten lookups, closed properly.
- DKIM.Whether Microsoft 365 signing selectors are published, so receivers can verify mail was not altered.
- DMARC.Whether a policy exists and whether it actually enforces anything, or is sitting at p=none collecting reports.
These three decide whether receivers trust mail from a domain, and whether someone else can send mail pretending to be it. Gmail, Yahoo and Microsoft now reject or junk bulk mail from domains without them, so this affects your own delivery as much as your exposure to impersonation.