DKIM Key Rotation

What is DKIM Key Rotation?

DKIM key rotation is the practice of regularly replacing the cryptographic key pairs used for DomainKeys Identified Mail (DKIM) authentication. It helps maintain security and trust by minimizing the risk that a compromised or outdated key could be used to forge valid email signatures.

Each DKIM key pair consists of a private key (stored on the mail server and used to sign outgoing emails) and a public key (stored in DNS, allowing receiving servers to verify those signatures). Regularly rotating these keys ensures that even if one is exposed, its window of usefulness is short-lived.

How DKIM Key Rotation Works

Rotating DKIM keys involves three coordinated steps:

1. Create a new key pair – Generate a new private and public DKIM key.
2. Publish the new public key – Add it to DNS under a new selector (e.g., s=mail2025).
3. Update the mail server – Configure it to sign outgoing messages using the new private key and selector.

During the transition, both old and new keys can coexist. Incoming mail may still be validated with the old selector while new mail is signed with the new one. After a safe period, once all messages signed with the old key have passed through the system, the old key can be safely removed from DNS.

A well-planned rotation policy typically refreshes DKIM keys every 6–12 months, depending on the organization’s security requirements.

The Role of DKIM Key Rotation in Email Security

Rotating DKIM keys protects against long-term key exposure and cryptographic weaknesses. If attackers obtain a private key or exploit a misconfigured DNS record, they could impersonate your domain and bypass authentication. Key rotation limits that damage window and reinforces the trustworthiness of your email infrastructure.

It also improves compliance posture for organizations following strict security frameworks (such as ISO 27001 or SOC 2), where key management hygiene is a documented requirement.

DKIM Key Rotation and DMARCeye

DMARCeye helps you track and monitor DKIM selectors and keys over time, ensuring that outdated or inactive keys are identified and rotated promptly.

By analyzing your DMARC reports, DMARCeye highlights which selectors are being used, which ones have gone silent, and whether your DKIM configurations align with active mail streams. This visibility enables secure and predictable key management, without the risk of breaking email authentication.

Sign up for a free trial of DMARCeye today and secure your email domain.

To learn more about DMARC and DMARC-related terms, explore the DMARCeye Glossary.