DKIM Validator

What is DKIM?

DomainKeys Identified Mail (DKIM) is an email authentication protocol designed to protect email senders and recipients from forgery and spoofing. It works by allowing the sending domain to sign its outgoing emails with a unique cryptographic signature, which recipients can verify using a public key published in the sender's DNS records. This process ensures the integrity and authenticity of the email.

Why is DKIM Important?

• Authentication and Trust: DKIM builds trust by verifying that an email hasn’t been tampered with and originates from the claimed domain.
• Protection Against Spoofing: It helps prevent attackers from impersonating your domain to send fraudulent emails.
• Improved Email Deliverability: Emails with valid DKIM signatures are less likely to be flagged as spam.
• Compatibility with Other Protocols: DKIM works alongside SPF and DMARC to strengthen email authentication.

How Does DKIM Work?

1. Key Pair Generation: The sender generates a public-private key pair. The private key signs emails, and the public key is published in the DNS as a TXT record.
2. Signing Emails: When an email is sent, the private key adds a DKIM signature to the email header.
3. Verification by Recipient: The recipient's mail server retrieves the public key from the DNS and verifies the DKIM signature.

Common DKIM Issues

• Incorrect DNS Configuration: Errors in publishing the public key or TXT record formatting can cause failures.
• Selector Misconfiguration: Mismatched selectors in the email header and DNS record lead to verification issues.
• Expired or Rotated Keys: Failure to update DNS with new public keys during key rotation can break authentication.
• Message Body Changes: Modifications to the email body by intermediate servers can invalidate the DKIM signature.
• Key Size Issues: Some servers reject shorter keys (e.g., 1024 bits), while older systems may not support longer keys (e.g., 2048 bits).
• Mismatch with SPF and DMARC: A valid DKIM signature is essential for DMARC alignment.

How to Ensure a Strong DKIM Setup

• Use a Long Key Length: Prefer 2048-bit keys or longer for robust security.
• Check Selector Consistency: Ensure DNS records match the selectors used by your mail server.
• Rotate Keys Periodically: Regularly update DKIM keys to reduce the risk of compromise.
• Test Regularly: Use our DKIM validation tool to check configuration and compliance with RFC standards.
• Integrate with DMARC: Combine DKIM with DMARC to enforce authentication policies and monitor domain usage.