Methodology and editorial policy
How each check works, which data sources it uses, what it can't tell you, how lookups are handled, and how guides are written, reviewed and corrected.
On this page
How the checks work
All checks run live when you ask for them. Most run in your own browser, which sends the queries directly to the public services named below; a few run on our server because a browser can't make them. The only reuse is Globalping results for the same target and region within one minute.
| Check | Data source | Notes |
|---|---|---|
| DNS records, MX, SPF, DKIM, DMARC, BIMI | Public recursive resolvers: Cloudflare 1.1.1.1, with Google 8.8.8.8 as a fallback | You see what most of the internet sees, including cached answers and their remaining TTL |
| SPF validation | Our implementation of RFC 7208 check_host() | Evaluates whole CIDR ranges exactly; enforces the 10-lookup and 2-void-lookup limits |
| Nameserver provider | A maintained list of DNS provider hostnames, then RDAP registration of the nameserver's IP | Shows which method identified each provider |
| IP Whois | RDAP from ARIN, following referrals to RIPE NCC, APNIC, LACNIC and AFRINIC | Only the five registries are contacted |
| Domain Whois | RDAP through the rdap.org bootstrap service, then the registry's own RDAP server | Registrant details are often redacted. A few country-code domains have no RDAP service yet |
| Blocklists | 20 DNS blocklists queried from your browser; Spamhaus from our server through its Data Query Service | A list that doesn't answer, or answers with an error code, is reported as "no answer", never as clean or listed |
| Reverse DNS | PTR lookup plus forward confirmation | The same test Gmail applies to sending IPs |
| Ping, traceroute, DNS propagation | Globalping probes worldwide; if Globalping is unavailable, an HTTPS reachability check from our server, clearly labelled | Globalping measurement data, including the target, is public; probe locations are approximate |
| Network owner (What Is My IP?) | RDAP registration data and RIPEstat routing data | The country is where the block is registered; no city estimate |
How findings are graded
- Fail: breaks delivery, resolution or authentication, or violates a published standard (an RFC or a mailbox provider's stated requirement).
- Warning: works today, but is risky, deprecated, or close to a hard limit.
- Pass: checked and correct.
- Note: context that doesn't need action.
A DNS query that times out or fails is reported as "couldn't check", never as a missing record.
What the checks can't tell you
- DNS shows what a domain publishes, not whether each sending platform actually signs or aligns. Check real message headers for that.
- Apart from Globalping measurements, DNS results reflect public resolvers. Internal (split-horizon) DNS and geo-routed answers can differ for you.
- Blocklist results show listings at the moment of the check; lists change hourly.
Privacy of lookups
Domains, IP addresses and other values you enter are used to run the check and then discarded. They aren't stored by this site. Running a check does send queries to third parties: DNS resolvers, registries and blocklist operators (directly from your browser, so they see your IP address), and Globalping for ping, traceroute and propagation checks (from our server). Report links (/report/<domain>) carry the domain in the URL and re-run the checks each time they're opened. Pages that show your own IP are never cached. See the privacy policy.
Editorial policy
- Written for practitioners. Every guide starts with the answer, shows real record syntax, and links primary sources: RFCs and mailbox providers' own documentation.
- How guides are produced. Drafts are prepared with the help of AI writing tools, then reviewed, tested against real systems, corrected and expanded with first-hand experience by James Bayliss before publication. Nothing is published without that review, and each guide shows its review date. [James — keep, edit or remove this disclosure as you see fit.]
- Independence. No vendor pays for coverage or reviews content before publication. Advertising is placed by Google AdSense, labelled as such, and kept apart from tool controls and results.
- Updates. Guides are re-reviewed at least every six months, and sooner when a standard or a provider requirement changes.
- Corrections. Report errors through the contact form. Confirmed errors are fixed promptly; corrections that change a guide's advice are noted at the end of the guide with the date.