DomainKeys Identified Mail (DKIM)
An email authentication method that adds a cryptographic signature to outgoing mail so recipients can verify the message genuinely came from your domain and wasn't altered in transit.
What DKIM is
DKIM (DomainKeys Identified Mail) adds a digital signature to outgoing email. The sending server signs the message with a private key; the recipient verifies the signature using a public key published in your DNS records.
A valid signature tells the recipient two things: the message genuinely originated from a system authorized for your domain, and the message content wasn't altered in transit.
DKIM works alongside SPF and DMARC. Where SPF authorizes sending servers, DKIM proves the message itself is authentic and intact.
Why DKIM matters for your firm
For firms sending tax documents, financial statements, and client communications, proving a message is genuine and unmodified is part of maintaining client trust.
DKIM is also a prerequisite for DMARC enforcement. Without a valid DKIM signature (or aligned SPF), DMARC cannot confirm that a message is legitimately from your domain.
A weak, missing, or misconfigured DKIM setup can mean your mail isn't signed at all — or that the signature doesn't align with your visible From: domain.
What we look at
- Whether DKIM signing is in place for outbound mail from your domain.
- Which selector records are published and whether the public keys are retrievable.
- Whether signatures align with your visible From: domain.
- Key configuration and whether signing covers the parts of the message that matter.
This review uses publicly available information and does not log into private systems or access private client records. Any deeper testing that requires authorization only takes place after you authorize it and the scope is agreed upon.
Keep exploring
See how DKIM applies to your firm.
The RingWarden Professional Security Assessment reviews dkim and the rest of your public-facing digital infrastructure, then delivers a clear written report.
One-time payment. Professional written report. Delivered within 3 business days of confirmed payment, subject to the necessary assessment scope and access arrangements.