DKIM management
Sendmarc’s email authentication solution offers powerful DKIM management capabilities created to simplify, safeguard, and optimize DKIM records across any domain setup.
Through seamless DKIM key import, secure key storage and rotation, plus quick DKIM record verification, Sendmarc empowers organizations to maintain trusted cryptographic signatures that confirm message integrity and prevent email fraud.
Whether your company manages a few domains or thousands, Sendmarc delivers the tools, visibility, and insight needed to streamline DKIM operations and boost email security.
DKIM management & setup
DKIM key hosting & rotation
DKIM record validation
DKIM & DMARC integration
Enterprise capabilities for all
DKIM key importing
DKIM key hosting & encryption
DKIM key rotation
DKIM record validation
Continuous monitoring
DMARC integration
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Safeguard your company’s domains from email tampering and improve its credibility with Sendmarc’s advanced DKIM management capabilities.
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What is DKIM
(DomainKeys Identified Mail)?
Why is DKIM important for email authentication?
DomainKeys Identified Mail (DKIM) is a critical email authentication protocol that ensures the integrity and authenticity of email messages. It uses cryptographic signatures to verify that an email hasn’t been tampered with during transit. This is particularly important in combating Man-in-the-Middle (MitM) attacks and email tampering. The protocol is essential because it:
- Reduces message modification: Decreases the chance of emails being changed during transit, helping them reach recipients’ inboxes unaltered
- Enhances email deliverability: When combined with Sender Policy Framework (SPF) and Domain-based Message Authentication, Reporting, and Conformance (DMARC), the protocol improves the likelihood of emails reaching their intended destination
- Improves reputation: Verifying that email content is genuine builds trust with customers and stakeholders, enhancing the sender’s domain reputation and credibility
How does DKIM work?
The email authentication standard uses cryptographic signatures to protect domains from impersonation. It operates by leveraging a unique private-public key pair:
- Private key: This key is exclusive to the organization’s sending infrastructure and is used to sign each outgoing email.
- Public key: This key is stored in the DNS settings as a TXT or CNAME record. It allows receiving email servers to verify the authenticity of an email.
The process works as follows:
- A unique private key provides a cryptographic signature for each outgoing email
- The receiving email server fetches the public key from the sender’s DNS record
- The receiving server uses the public key to decrypt the signature and verify its authenticity
If the signature matches, the message is considered authentic. If the signature doesn’t match, the recipient server might handle the email based on its configured DMARC policy. The email could then be monitored or flagged as suspicious, meaning it’ll be placed in the Spam folder and quarantined or rejected outright.
Interested in learning more?
Discover how our advanced email security platform automates this process to save time, reduce costs, and simplify protocol management.
Benefits of using DKIM
Implementing the protocol offers multiple advantages for those looking to secure their email communications. After the correct configuration, the standard helps to:
- Prevent email tampering: It protects recipients from MitM attacks, a common form of which sees emails being intercepted and altered during transit. By verifying the integrity of email content, the standard ensures that messages remain unaltered and trustworthy.
- Enhance deliverability: Signed emails are less likely to be flagged as Spam or rejected by receiving servers. When combined with SPF and DMARC, the protocol strengthens email authentication and improves inbox placement.
- Survive auto-forwards: Signatures remain valid as long as the email content remains unchanged after leaving the sender. This ensures that forwarded emails can still be authenticated, even if other verification methods fail.
- Strengthen reputation: Using the protocol shows a commitment to secure and trustworthy email practices. This builds confidence among customers, partners, and stakeholders, enhancing domain reputation and supporting long-term brand trust and engagement.
Common DKIM implementation mistakes
When setting up the protocol, it’s essential to avoid these common mistakes to ensure effective email authentication and security:
- Incorrect DNS configuration: Improperly configured DNS settings can lead to verification failures, causing emails to be marked as Spam or rejected. Always double-check DNS entries for accuracy and syntax.
- Irregular key updates: Regularly updating keys helps prevent security breaches caused by compromised or outdated keys.
- Shorter key lengths (less than 2048 bits): Keys shorter than 2048 bits are vulnerable to cyberattacks, compromising your business’s email security. Always use 2048-bit keys for strong protection.
- Early email signing: Signing emails before they’re altered by tools like signature managers can result in authentication failures. Ensure emails are signed only at the last hop before they’re sent over the internet.
- Failure to verify record changes: If DNS records aren’t properly verified after updates, email authentication might fail, leading to delivery issues.
DKIM record example
| Host | Type | Value |
|---|---|---|
| selector._domainkey.yourdomain.com | TXT | v=DKIM1; k=rsa; p=[YourPublicKeyHere] |
Here’s a CNAME record example:
| Host | Type | Value |
|---|---|---|
| selector._domainkey.yourdomain.com | CNAME | selector.domainkey.providerdomain.com. |
How to set up a DKIM record (step-by-step)
Follow these clear steps to set up DKIM for your company’s domain effectively:
Step 1: Generate the keys
Begin by configuring your organization’s email provider. This process generates a private and public key pair. The exact steps depend on the provider – for example, Google and Microsoft have unique methods – but the outcome is always a public key for your business to publish in its DNS settings.
Some providers only issue the public key, but a private key can be created using tools like Sendmarc’s key generator, which provides one quickly and for free, simplifying the process.
Step 2: Publish the DNS record
Add the generated public key to the DNS record. This allows receiving email servers to access the signature information needed to verify the emails.
Step 3: Verify and test the setup
Use a verification tool, such as Sendmarc’s DKIM lookup, to ensure the record is correctly configured.
Plus, your company can analyze email headers with Sendmarc’s header analysis tool to confirm that its emails are being properly signed.
Regular monitoring of these headers helps identify misconfigurations or unauthorized changes. Frequently reviewing authentication results ensures everything remains correctly configured, especially after updates to email systems or DNS records.
DKIM, SPF, and DMARC: Enhancing email security
Combining the protocol with SPF and DMARC provides a comprehensive email authentication strategy. Each standard plays a role in securing email communications:
- SPF: Specifies which email servers are authorized to send messages on behalf of a domain, reducing the risk of domain spoofing
- DMARC: Adds an extra layer of control by defining policies for handling unauthenticated emails and providing detailed reports on authentication results and failures
Why combine the protocols?
Using all three ensures powerful protection against phishing, spoofing, and other email-based threats. This combination also improves the deliverability of communications by increasing trust with email providers.
DKIM FAQs
What is DKIM used for?
DomainKeys Identified Mail (DKIM) is an email authentication method that’s used to verify the authenticity and integrity of email messages. It ensures that emails haven’t been altered during transit. DKIM helps prevent Man-in-the-Middle (MitM) attacks by attaching a digital signature to outgoing emails, which is verified using public key cryptography.
What is the difference between DMARC and DKIM?
DKIM verification focuses on the authenticity and integrity of individual emails by using cryptographic signatures. Domain-based Message Authentication, Reporting, and Conformance (DMARC) builds on DKIM and Sender Policy Framework (SPF) by providing policies for handling authentication failures and reporting mechanisms. While DKIM validates individual emails, DMARC ensures alignment between the ‘From’ address and authentication methods, offering better protection against domain impersonation.
How do I know if my email is DKIM-enabled?
If your organization wants to check if its email is DKIM-enabled, it can inspect the email headers of a sent message using our header analysis feature. Or use our DKIM lookup tool to verify there’s a record in your business’s domain DNS settings.
Can I have multiple DKIM records for my domain?
Yes, your company can have multiple DKIM records for its domain. Each record uses a unique selector, which is included in the email’s DKIM signature – this shows which key was used for validation. This setup is useful when managing multiple email services or transitioning between keys.
How can I check if my DKIM record is set up correctly?
To check if a DKIM record is correctly set up, use online tools like Sendmarc’s DKIM lookup. This tool performs a DNS lookup to verify that the public key associated with your organization’s domain matches the private key used to sign outgoing emails.
Book a demo with Sendmarc to find out how we can help secure your business’s email communications and protect its domain from evolving cyberthreats.
