Welcome to checkdmarc’s documentation

A Python module, command line utility, and web application for validating SPF and DMARC DNS records.

Note

This project is maintained by one developer. Please consider sponsoring my work if you or your organization benefit from it.

Features

• API, CLI, and web interfaces

• Can test multiple domains at once

• CLI output in JSON or CSV format

• 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 sp values, or by use of the pct/rf/ri tags that were removed in RFC 9989

  • Checks for authorization records on reporting email addresses

• BIMI

  • Validation of the mark format and certificate against the Minimum Security Requirements for Issuance of Mark Certificates

  • Parsing of the mark certificate

• MX records

  • Preference

  • IPv4 and IPv6 addresses

  • Checks for STARTTLS

  • Use of DNSSEC/TLSA/DANE to pin certificates

• MTA-STS

• SMTP TLS reporting

  • Record and policy parsing and validation

• SOA record parsing

• Nameserver listing

Further reading

• Installation
• CLI
• Environment variables
• API

Indices and tables

• Index

• Module Index

• Search Page