DomainKeys Identified Mail (DKIM) Defined

DomainKeys Identified Mail (DKIM) is an email authentication method designed to detect and prevent email spoofing. It allows the sender to attach a digital signature to the email header, which is then verified by the recipient's mail server to ensure the email has not been altered in transit and that it was indeed sent from the claimed domain.

How It Works:

  1. Digital Signature: When an email is sent, the sender’s mail server generates a unique cryptographic signature based on the email's content and headers.
  2. Public Key Publishing: The sender’s domain publishes a public key in the DNS (Domain Name System) records.
  3. Verification: The recipient’s mail server retrieves the public key from the DNS and uses it to verify the signature. If the signature matches the email content, the email is authenticated.

Learn why DNS authentication is paramount when it comes to deliverability and security and how to handle email authentication with OneSignal.

How to Use it in a Sentence

Implementing DKIM in your email marketing strategy ensures that your emails are authenticated, enhancing deliverability and building trust with your recipients by verifying that the messages are genuinely from your domain.

Common FAQs

DKIM is important because it enhances email security, improves deliverability by reducing the likelihood of emails being marked as spam, and helps maintain the sender’s domain reputation by verifying the authenticity of the emails.

To implement DKIM for your OneSignal email, check out our DNS Documentation Guide.

While DKIM significantly reduces the risk of email spoofing by verifying the sender’s domain and the integrity of the email content, it is most effective when used in conjunction with other authentication methods like SPF and DMARC.

You can check if your emails are DKIM signed by looking at the email headers in your email client. Look for a header that starts with “DKIM-Signature.” You can also use online tools to analyze your email headers for DKIM signatures.

If a DKIM signature fails verification, the recipient’s mail server may mark the email as suspicious or spam. This can negatively impact deliverability and the sender’s domain reputation. It's important to monitor and maintain proper DKIM implementation to avoid such issues.

It’s recommended to periodically update your DKIM keys to maintain security. The frequency of updates can vary based on your organization’s security policies, but a common practice is to rotate keys every 6 to 12 months.

Most major email providers support DKIM and use it as part of their email authentication and anti-spam measures. For more information on how to authenticate your OneSignal emails, check our DNS Authentication Guide.

Yes, DKIM is often used in conjunction with other email authentication methods like SPF and DMARC to provide a comprehensive approach to email security and authentication.

If you have questions or need assistance with setting up and optimizing DKIM for your email campaigns, email us at