DKIM Inspector

DKIM Inspector analyzes the DKIM-Signature header in an email to verify that the signature was generated with a valid public key and that it covers the declared headers and body, as specified by RFC 6376. It is designed for security teams, system administrators, and developers who need to confirm that mail signing is correctly configured for a domain.
Conceptually, the tool parses the signing domain (d) and selector (s), identifies the list of headers included (h), and reads bh (body hash) to compare against the calculated body hash. It then retrieves the public key from DNS at s._domainkey.d and uses RSA verification against the canonicalized header and body to determine validity.
Unique value: it supports multiple signatures in a single message, reports per-signature results, surfaces common misconfigurations (wrong selector, missing DNS TXT, mismatched body hash), and provides guidance for remediation. Core features include header/body canonicalization, DNS key lookup, cryptographic verification, and structured result data for automation.
Use cases include email deliverability troubleshooting, security auditing, and automation pipelines for mailbox providers and security platforms; it enables developers to integrate DKIM checks into CI/CD, incident response, or monitoring workflows.