About

Why build yet another SPF/DMARC/email security validation website? I'm glad you asked. Many such websites are created by vendors as a way of pitching their product or service. Domain Checkup is an open source website that provides all information about a domain's DNS-based email security controls on one page. The web frontend, web backend, and underlying library are all open source projects. So, you can get a quick, helpful overview of a domain's configuration, or dive into the source code to see exactly how a protocol works, all without a sales pitch.

Features

  • Responsive, mobile-first UI using Bootstrap
  • Can be installed as a Progressive Web Application (PWA) on mobile devices and computers
  • Provides all details from the checkdmarc library and CLI tool on a single page
    • DNSSEC validation
    • SPF
      • Record validation
      • Counting of DNS lookups and void lookups
      • Counting of lookups per mechanism
    • DMARC
      • Validation and parsing of DMARC records
      • Shows warnings when the DMARC record is made ineffective by pct or sp values
      • Checks for authorization records on reporting email addresses
    • BIMI
      • Validation of the mark format and certificate
      • Parsing of the mark certificate
    • MX records
      • Preference
      • IPv4 and IPv6 addresses
      • Checks for STARTTLS (optional; currently disabled on the production website)
      • Use of DNSSEC/TLSA/DANE to pin certificates
    • MTA-STS
      • Record parsing and validation
    • SMTP TLS reporting (TLSRPT)
      • Record and policy parsing and validation
    • SOA record parsing
    • Nameserver listing