Summary
Even when DKIM records appear accurate, validation failures can arise from a multitude of issues related to DNS configuration, record syntax, and environment. Key areas of concern include incorrect DNS hosting, propagation delays, record format, key lengths, selector conflicts, and DNS inconsistencies. DNS providers can automatically append domain names, convert underscores, or truncate long records. External factors such as firewalls, shared hosting configurations, and domain reputation can also influence DKIM validation. Therefore, troubleshooting involves verifying DNS settings, record syntax, DNS propagation, selector uniqueness, domain reputation, and the use of external validation tools to confirm the actual state of the records.
Key findings
- DNS Configuration: Incorrect DNS hosting, missing DKIM keys, and DNS propagation delays are common causes of validation failures.
- Record Syntax and Format: Syntax errors, incorrect record types (non-TXT), and DNS server truncation can invalidate DKIM records.
- Selector and Key Issues: Incorrect selectors, overlapping selectors, and incorrect key lengths can cause DKIM validation failures.
- DNS Provider Behavior: DNS providers may automatically append domain names or convert underscores, leading to incorrect DKIM records.
- External Factors: Firewalls, shared hosting configurations, and domain reputation can influence DKIM validation.
- DNS Inconsistencies: What you configure may not be what is visible externally due to DNS inconsistencies.
Key considerations
- Verify DNS Settings: Check DNS hosting, ensure DKIM keys are present, and allow sufficient time for DNS propagation.
- Review Record Syntax: Ensure the DKIM record is a TXT record, correctly formatted, and doesn't exceed character limits.
- Ensure Selector Uniqueness: Each sending service should use unique selectors to prevent conflicts.
- Monitor Domain Reputation: Regularly check domain reputation and address any blacklisting issues.
- Use Validation Tools: Employ external tools to verify the actual state of DKIM records and troubleshoot validation failures.
- Firewall configuration: Review firewall settings to ensure they are not interfering with DNS lookups.
What email marketers say
12 marketer opinions
Even when DKIM records appear accurate, validation failures can stem from a variety of underlying issues. These include DNS configuration problems (such as incorrect hosting or propagation delays), syntax errors in records, incorrect key lengths, overlapping selectors, DNS provider modifications, firewall interference, shared hosting misconfigurations, and domain reputation issues. Proper selector and domain verification, cache flushing, and double-checking DNS settings are crucial for resolving these problems.
Key opinions
- DNS Configuration: Incorrect DNS hosting or propagation delays can prevent DKIM records from being validated.
- Syntax Errors: Syntax errors like extra spaces, incorrect characters, or line breaks in the DNS record can cause failures.
- Key Length & Selectors: Incorrect DKIM key lengths and overlapping selectors can lead to validation problems.
- DNS Provider Issues: DNS providers may automatically append domain names or convert underscores, causing DKIM records to be invalid.
- Shared Hosting: Misconfigurations by other users on shared hosting environments can affect domain reputation and DKIM validation.
- Domain Reputation: Poor domain reputation can cause email providers to temporarily reject emails with invalid DKIM signatures.
Key considerations
- Verify DNS Hosting: Confirm that the DNS records are hosted with the correct provider and that the changes have propagated.
- Check Record Syntax: Double-check the syntax of the DKIM record for any errors, including extra characters and ensure it is a TXT record.
- Unique Selectors: Ensure that each sending service uses unique selectors to avoid conflicts.
- Monitor Domain Reputation: Regularly check the domain's reputation and address any blacklisting issues.
- Cache Flushing: Flush the DNS cache after making changes to ensure resolvers fetch the updated records.
- Firewall Configuration: Review firewall settings to ensure they are not interfering with DNS lookups.
Marketer view
Email marketer from Mailjet explains that if you've recently changed your DKIM records, the old records might be cached by DNS resolvers. Flush your DNS cache or wait for the cache to expire to ensure resolvers fetch the updated records. Your ISP can help you to do this if you're not technical.
13 Dec 2023 - Mailjet
Marketer view
Email marketer from EmailGeeks Forum suggests checking if there are any firewalls or security settings blocking access to your DNS records. Some firewalls may interfere with DNS lookups, preventing email servers from verifying your DKIM signature.
3 May 2025 - EmailGeeks Forum
What the experts say
3 expert opinions
Even with seemingly accurate DKIM records, validation failures often point to DNS misconfigurations or inconsistencies. The published DKIM key might be missing, or the hostname setup may be incorrect. It's critical to verify the record's actual existence and content using external tools, as what is configured may not be what is visible to the outside world.
Key opinions
- DNS Misconfiguration: Incorrect DNS configuration, particularly with hostname setup, is a primary cause of DKIM validation failure.
- Missing DKIM Key: The DKIM key may not be published at the expected hostname, leading to validation issues.
- DNS Inconsistencies: What you think is published in DNS may not be what's actually visible externally, causing validation failures.
Key considerations
- Check Hostname: Verify that the hostname is set up correctly in your DNS configuration.
- Verify Key Publication: Ensure the DKIM key is published at the correct hostname using external DNS lookup tools.
- Use External Validation Tools: Employ external tools like those provided by Word to the Wise to verify the DKIM record's existence and accuracy from an outside perspective.
Expert view
Expert from Email Geeks says there is no DKIM key published at whdyp2ro6wufcdub23jrq4i74jghn2gh._<http://domainkey.egoswim.com|domainkey.egoswim.com> and there is also no DKIM key published at flodesk._<http://domainkey.egoswim.com|domainkey.egoswim.com>.
18 May 2024 - Email Geeks
Expert view
Expert from Email Geeks indicates the problem is likely an incorrect DNS configuration, specifically with the hostname setup. Laura asks for the selector to find the hostname.
15 Oct 2021 - Email Geeks
What the documentation says
5 technical articles
Even when DKIM records appear accurate, validation failures often stem from issues like incorrect DNS record setup, syntax errors, DNS propagation delays, incorrect record types, or DNS server truncation. It's crucial to ensure the selector and domain match, verify the record is published as a TXT record, allow sufficient time for DNS propagation, and ensure the DKIM record is correctly formatted without exceeding character limits or being truncated.
Key findings
- DNS Record Setup: Incorrect DNS record setup is a common reason for DKIM validation failure, including missing records, typos, or lack of propagation.
- Syntax Errors: Syntax errors in the DNS record, such as extra spaces, incorrect characters, or line breaks, can cause validation issues.
- DNS Propagation: DNS propagation delays can lead to temporary DKIM validation failures.
- Incorrect Record Type: DKIM records must be published as TXT records and not as CNAME or other record types.
- DNS Server Truncation: DNS servers may truncate long DNS records, causing validation problems for long DKIM keys.
Key considerations
- Verify Selector and Domain: Ensure the selector and domain in the DKIM record match the signing domain.
- Check Record Format: Verify the DKIM record is correctly formatted, including the presence of 'v=DKIM1; k=rsa; p=...'.
- Allow Propagation Time: Allow sufficient time for DNS records to propagate across the internet after updates.
- Use TXT Record: Confirm the DKIM record is published as a TXT record.
- Avoid Truncation: Ensure the DKIM record is a single string and doesn't exceed character limits to prevent DNS server truncation.
Technical article
Documentation from AWS Documentation shares that DNS propagation delays can cause temporary DKIM validation failures. After updating DNS records, allow sufficient time (up to 48 hours) for the changes to propagate across the internet. Use DNS lookup tools to verify the record's presence.
23 May 2023 - AWS Documentation
Technical article
Documentation from Google Workspace Admin Help explains that a common reason for DKIM validation failure is incorrect DNS record setup. The record may be missing, have typos, or not be propagated yet. Ensure the selector and domain match the signing domain.
14 May 2022 - Google Workspace Admin Help
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