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DNS lookup Mail server DNSSEC SPF

DNS lookup Every record type, with its TTL and the DNSSEC validation state. Propagation The same question asked of five public resolvers and of your authoritative servers. Reverse lookup From an IP address to its name, and a check that the round trip agrees. Domain record Availability, registrar, dates and locks, read from the registry RDAP. Punycode / IDN Conversion both ways, with detection of look-alike characters. Mail server MX, reverse DNS, FCrDNS, open ports, SMTP banner and the certificate served. SPF Analysis and generation, with the real count of DNS lookups triggered. DKIM Public key readout, length, algorithm and detection of revoked keys. DMARC Policy readout, guided generation and validation of report recipients. MTA-STS Policy, TXT record and a check that the policy is actually being served. Email headers Path taken, delays, authentication results. Analysed in your browser. DNSSEC DS to DNSKEY chain, algorithms in use and confirmation that validation holds. CAA Which authorities may issue a certificate for this domain, and generation. SEO and AI visibility Tags, robots.txt, sitemap, security headers and the policy towards AI crawlers.

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MTA-STS

Policy, TXT record and a check that the policy is actually being served.

Domain

Build a policy

Produces the three pieces to publish, which must stay consistent with each other.

Mode

testing — report failures without ever blocking — the starting step

enforce — refuse delivery if the policy is not honoured

none — explicitly cancel an earlier policy

Receiving servers

One per line. The wildcard covers a single level: *.example.com covers mx1.example.com but not a.mx1.example.com nor example.com.

Cache lifetime

How long a sender keeps the policy. The longer it is, the better it protects — and the longer a correction takes to spread.

Hosted on oxmo.org

No diagnostic data kept beyond a five-minute cache.

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