What is the most common reason for DKIM records not validating even when they appear correct?

If your DKIM records seem correct but aren't validating, the primary reason is often that your domain's DNS is not actually hosted where you think it is. Many users mistakenly add records to a registrar's interface when their DNS is delegated to a different service, like a web host, CDN ( Cloudflare ), or e-commerce platform ( Shopify ). You need to identify the authoritative DNS provider using an NS record lookup.

Can I have multiple DKIM records for the same domain, and could they cause validation issues?

Having multiple DKIM records for the same domain (e.g., from different ESPs or services like Amazon SES and Flodesk) is perfectly acceptable, provided each record uses a unique selector. Each selector points to a different public key. The issue arises if there are conflicts in the selector names, if records are incorrectly published, or if your email service is trying to sign with a selector not present or active in DNS.

What steps should I take to troubleshoot DKIM validation problems?

You can troubleshoot by first confirming your actual DNS host via an NS record lookup. Then, verify that the DKIM records are published in the correct DNS interface and that their syntax, especially the hostname/name field, adheres to your provider's requirements. Inspect the raw headers of an email sent from your domain for the Authentication-Results header, which often provides a specific reason for failure. Also, consider if email forwarding or mailing lists are modifying the message content.

Do DNS providers sometimes automatically add my domain name to DKIM records, causing issues?

Yes, some DNS providers automatically add your domain name to the end of the record's name/host field. For example, if you input selector1._domainkey , the provider might internally create selector1._domainkey.yourdomain.com . If you then add selector1._domainkey.yourdomain.com yourself, the result could be selector1._domainkey.yourdomain.com.yourdomain.com , which is incorrect. Always check your DNS provider's specific instructions or test the record after publication.

Why aren't my DKIM records validating even though they are accurate? - Technical - Email deliverability - Knowledge base

It is a frustrating scenario: you have meticulously copied and pasted your DKIM records into your DNS, double-checked every character, and yet, they simply will not validate. It feels like you've done everything correctly, so why is your DomainKeys Identified Mail (DKIM) authentication still failing? This is a common challenge that many senders face, and it often points to nuances beyond simple record accuracy.

The core purpose of DKIM is to ensure the integrity and authenticity of your emails. It works by adding a digital signature to your outbound messages. Recipient mail servers then use a public key, published in your domain's DNS, to verify this signature. When validation fails, it indicates that the receiving server could not match the signature to the public key, suggesting either a problem with the record itself or, more commonly, an issue with how the record is being read or applied in the broader DNS ecosystem.

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The foundations of DKIM validation

DKIM functions on a cryptographic pair: a private key that signs your outgoing emails and a public key that resides as a TXT or CNAME record in your domain's Domain Name System (DNS). When an email is sent, the receiving mail server looks up your domain's DNS for the public key, specifically at the address indicated by the s= (selector) and d= (domain) tags within the email's DKIM-Signature header. If the public key found matches the signature, DKIM passes, confirming the email's authenticity and that it has not been tampered with since signing.

For many email service providers (ESPs), including

Amazon Simple Email Service (SES), your DKIM setup involves adding several CNAME records to your DNS. These records point to keys managed by the ESP, simplifying the process for senders. However, issues arise when these CNAMEs are not correctly published or resolved, leading to validation errors. You can find more details on troubleshooting DKIM issues in Amazon SES.

A common point of confusion is what constitutes the DKIM selector. It's the unique string that tells recipient servers which public key to look up for your domain, typically appearing before ._domainkey in your DNS record name. For example, in s1._domainkey.yourdomain.com, s1 is the selector. If the DNS entry is not discoverable or contains errors like improper formatting or extraneous characters, the DKIM check will fail. This is why many tools might say no DKIM record found, even if it appears correct in your DNS dashboard. A helpful resource for understanding these is a practical guide to DKIM selector name examples.

Unmasking DNS hosting confusion

One of the most frequent reasons for DKIM records not validating, despite appearing accurate, is incorrect DNS hosting. Many domain owners mistakenly assume their DNS is managed by their domain registrar (where they bought the domain). However, platforms like Shopify,

Cloudflare, or web hosts often take over DNS management when you connect your domain. This means that the DNS records you are diligently adding might be going into a DNS interface that isn't actually authoritative for your domain.

To verify where your domain's DNS is truly managed, you need to perform an NS (Name Server) record lookup. This will show you the authoritative name servers for your domain. If these name servers point to a provider different from where you're attempting to add records, that's your primary disconnect. For example, if your website is hosted on Shopify, its DNS might actually be managed by

Google Domains or a similar service that Shopify uses under the hood, even if you bought the domain from GoDaddy.

Example: Checking authoritative name serversBASH

$ host -tNS yourdomain.com
yourdomain.com name server ns-cloud-d4.googledomains.com.
yourdomain.com name server ns-cloud-d2.googledomains.com.
...

Another common pitfall involves DNS providers automatically appending your domain name to the Name or Host field of CNAME records. For instance, if you enter selector1._domainkey and your provider (like GoDaddy or some Shopify setups) automatically appends .yourdomain.com, the resulting record might become selector1._domainkey.yourdomain.com.yourdomain.com, rendering it invalid. Always test your records post-publication using a reliable email deliverability tester.

DNS Provider/Platform	Common behavior	DKIM record impact
GoDaddy	Often auto-appends domain name to CNAME records	Can result in redundant domain name, causing the DKIM record to be invalid.
Shopify (with Google Domains DNS)	DNS records are managed through Shopify interface, which uses Google Domains name servers.	Records must be added correctly in the Shopify DNS settings to propagate through Google Domains.
Cloudflare	Acts as CDN and DNS provider; records must be added directly in Cloudflare.	If Cloudflare is your DNS, records on other providers will not be found.

Navigating multiple DKIM setups

It is not uncommon for a domain to use multiple email sending providers. For instance, you might use one ESP for marketing emails and another for transactional emails. Each ESP typically requires its own set of DKIM records with unique selectors. In theory, having multiple distinct DKIM records for the same domain (even if from the same underlying infrastructure like

Amazon SES) should not cause conflicts if the selectors are distinct.

However, issues can arise if these multiple records are mismanaged or if there's confusion about which record is active. For example,

Amazon SES often provides three CNAME records for DKIM, but typically only one is actively used for signing at any given time, with the others reserved for key rotation. If you're trying to validate a specific selector that isn't the currently active one for signing, it might appear as if the record isn't validating, even if it is correctly published for future use.

When transitioning to a branded sending domain, ensure that the DKIM selectors generated for that domain are the ones being used in your email headers. A mismatch between the selector in the email header and the selectors published in DNS will always result in a DKIM failure. If you're encountering intermittent issues, it could be due to factors like intermittent DKIM validation failures with Office365.

Beyond DNS: message modification and other factors

Sometimes, your DKIM records are indeed perfectly accurate and published correctly, yet validation still fails due to message modification. This is a common issue when emails are forwarded or sent through mailing lists. When an email's headers or body content are altered after the original DKIM signature is applied, the signature becomes invalid, leading to a DKIM authentication failure. This can also result in a DKIM body hash failing.

Other subtle issues can also cause DKIM to fail, even if the records seem accurate. These include temporary DNS resolution issues (often seen as a DKIM tempError), issues with the DKIM public key itself (e.g., an invalid RSA public key error), or even specific ISP policies that might cause DKIM to fail at some ISPs but not others. These problems are less about the record's accuracy and more about the environment or processing of the email.

Inspect raw email headers

The most definitive way to troubleshoot DKIM validation issues is to examine the raw email headers of a message sent from your domain. Look for the Authentication-Results header. It will typically show dkim=pass or dkim=fail and often provide a reason for the failure, such as body hash did not verify or no key found. This information is invaluable for diagnosing the precise cause. Google's documentation provides further guidance on this.

Maintaining robust DKIM validation

Troubleshooting DKIM records that appear accurate but fail validation requires a systematic approach. The first step is always to confirm your domain's authoritative DNS provider, as this is the most common reason for records not being discoverable. Next, meticulously check the record syntax, especially concerning how your specific DNS provider handles domain appending.

Beyond DNS, consider external factors like email forwarding or mailing list processes that might modify your message content. Implementing DMARC with a p=none policy and monitoring your DMARC reports can provide invaluable insights into authentication failures, including those related to DKIM. This can show you why you are receiving DMARC failure reports even if authentication appears correct.

Views from the trenches

Best practices

Always verify your domain's authoritative DNS servers using NS record lookups before publishing any new records.

Understand your DNS provider's specific requirements for adding CNAME or TXT records, especially regarding automatic domain appending.

Use a DKIM record checker tool to confirm record visibility and accuracy from various global locations after publication.

Monitor your DMARC reports closely, as they provide detailed feedback on DKIM authentication status and failure reasons.

Common pitfalls

Assuming your DNS is managed by your domain registrar when it is actually delegated to a different service like Shopify, Squarespace, or Cloudflare.

Adding the full domain name to a DNS record when your provider automatically appends it, leading to a duplicated and invalid entry.

Not understanding which specific DKIM selector is active or being used by your email sending service at any given time.

Overlooking email content modification due to forwarding or mailing list processing, which invalidates the DKIM signature.

Expert tips

Ensure you differentiate between temporary DNS resolution issues (tempError) and permanent DKIM failures. Temporary issues often resolve on their own, while permanent ones require configuration changes.

When dealing with multiple ESPs, confirm that each service is configured to use a unique DKIM selector to prevent signature overlaps and validation conflicts.

Be aware that some email platforms, like Amazon SES or Microsoft 365, might have multiple DKIM CNAMEs for key rotation, but only one is actively signing emails at a time. All must be present.

If your emails are being forwarded, be aware that DKIM often breaks during this process unless the forwarding server re-signs the email, which is rare.

Expert view

Expert from Email Geeks says: It's crucial to confirm where a domain's DNS is actually hosted, as many users incorrectly assume it's where they purchased the domain. NS record lookups will reveal the authoritative name servers, which might not be what the user expects.

October 2, 2024 - Email Geeks

Marketer view

Marketer from Email Geeks says: We've experienced issues where DNS providers, like Shopify or GoDaddy, automatically append the domain name to CNAME records, even when it's already included, causing validation failures.

October 2, 2024 - Email Geeks