Summary
Gmail's 'cannot verify' message, despite authentication, is a multifaceted issue stemming from authentication configuration errors, reputation problems, atypical sending patterns, and forwarding practices. Incorrect or missing SPF, DKIM, and DMARC configurations are primary culprits. Additionally, factors such as poor IP/domain reputation, shared IP issues, inconsistent sending volumes, reverse DNS mismatches, and using third-party services incorrectly all contribute. Best practices such as maintaining clean lists, sender consistency, setting up feedback loops, and staying updated on authentication standards are crucial in resolving this issue.
Key findings
- Authentication Configuration: Incorrect or missing SPF, DKIM, and DMARC records, including syntax errors and alignment problems, are leading causes.
- Reputation Matters: Poor IP and domain reputation, stemming from blacklisting, spam complaints, or low engagement, can override successful authentication.
- Sending Practices: Inconsistent sending volumes, sending to unengaged recipients, and using shared IPs with poor reputations negatively affect deliverability.
- Third-Party Issues: Using third-party email marketing services incorrectly or routing email through servers with poor reputations can trigger warnings.
- Forwarding Problems: Forwarded emails commonly fail authentication because the forwarding server is not authorized to send on behalf of the original domain.
- Gmail Sending Route: Emails that are created within Google, then sent via 3rd party servers and back to Google can trigger verfication warnings.
Key considerations
- Validate Authentication Setup: Thoroughly check your SPF, DKIM, and DMARC records for accuracy, syntax, and alignment.
- Monitor Reputation: Regularly check your IP and domain reputation using online tools and take prompt action to address any issues.
- Maintain Sending Consistency: Establish consistent sending volumes and patterns, and avoid sudden spikes or sending to large numbers of new recipients.
- Practice List Hygiene: Clean your email lists regularly to remove unengaged, invalid, or spam-complaining addresses.
- Implement Feedback Loops: Set up feedback loops with major ISPs to identify and remove recipients who mark your emails as spam.
- Review Third-Party Configurations: Ensure that your third-party email marketing service is properly configured and authorized to send on your behalf.
- Avoid Forwarding: Discourage or avoid email forwarding whenever possible.
- Ensure direct sending: If sending emails via third parties, ensure they are not being created withing Google servers first before they are being sent.
What email marketers say
10 marketer opinions
Gmail's 'cannot verify' message, even with authentication, often stems from reputation-based issues, misconfigurations, or inconsistencies. Factors like poor IP/domain reputation, shared IP problems, inconsistent sending patterns, rDNS mismatches, third-party service misconfigurations, and lack of DMARC alignment contribute. Maintaining list hygiene, consistent sender information, and establishing feedback loops are also crucial.
Key opinions
- Reputation Matters: Poor IP and domain reputation, stemming from blacklisting, spam complaints, or low engagement, can override authentication success.
- Configuration Issues: Incorrect or incomplete configuration of SPF, DKIM, and DMARC, including DMARC alignment issues, causes verification failures.
- Sending Practices: Inconsistent sending volumes, sending to unengaged recipients, and using shared IPs with poor reputations negatively affect deliverability.
- rDNS Impact: Missing or mismatched reverse DNS (rDNS) records raise red flags about the legitimacy of the sending server.
- Third-Party Risks: Incorrect setup with a third-party email marketing service will cause Gmail to question email authenticity.
Key considerations
- Monitor Reputation: Regularly check your IP and domain reputation using online tools and address any issues promptly.
- Validate Authentication: Ensure your SPF, DKIM, and DMARC records are correctly configured and aligned, resolving any syntax errors or mismatches.
- Maintain Consistency: Establish consistent sending volumes and patterns, avoiding sudden spikes or sending to large numbers of new recipients.
- Clean Email Lists: Regularly remove unengaged, invalid, or spam-complaining email addresses from your list to improve sender reputation.
- Implement Feedback Loops: Set up feedback loops with major ISPs to identify and remove recipients who mark your emails as spam.
- Review Sender Information: Maintain consistent sender names and from addresses, and ensure they align with your domain authentication.
Marketer view
Email marketer from ZeroBounce says that sending emails to old, unengaged, or invalid email addresses can hurt your sender reputation and trigger Gmail warnings. Regularly clean your email list to remove these problematic addresses.
20 Feb 2024 - ZeroBounce
Marketer view
Email marketer from MailerQ explains that it's crucial to set up feedback loops with major ISPs like Gmail. Feedback loops notify you when recipients mark your emails as spam, allowing you to remove those recipients from your list and improve your reputation. Without them, you are flying blind.
29 Apr 2023 - MailerQ
What the experts say
7 expert opinions
Gmail's 'cannot verify' message can arise from unusual sending patterns, third-party server issues (reputation and location), or forwarding problems. Even with correct authentication, messages created within Google, routed through a third-party with a questionable reputation, and then returning to Google can trigger the warning. Furthermore, changes to authentication standards require adherence and that list washing does not work.
Key opinions
- Unusual Sending Patterns: Routing emails through a third-party server before sending to Gmail (especially if created at Google) can trigger verification warnings.
- Third-Party Server Reputation: The reputation and location of the third-party server (e.g., within OVH space, generic rDNS) contribute to deliverability issues.
- Forwarding Issues: Forwarded emails often fail authentication because the forwarding server isn't authorized to send on behalf of the original domain.
- Authentication Standards: Adhering to updated authentication standards is vital to ensuring the deliverabilty of your emails.
- List Washing issues: List Washing does not guarantee any increase in deliverability and shouldn't be used.
Key considerations
- Test Direct Sending: Trigger a message directly from the third-party server to Gmail to isolate the issue's origin.
- Evaluate Third-Party Server: Assess the reputation and configuration of any third-party mail server used in the sending process.
- Avoid Forwarding: Discourage or avoid email forwarding, as it often breaks authentication.
- Review Authentication Requirements: Carefully review and adhere to any changes in email authentication requirements from providers like Gmail.
- Avoid List Washing: List washing services do not help with inbox placement. Remove bad emails using list validation at point of capture instead.
Expert view
Expert from SpamResource explains that forwarded emails often fail authentication checks because the forwarding server isn't authorized to send on behalf of the original domain. This can lead to Gmail displaying a verification error even if the original email was properly authenticated.
12 Dec 2021 - SpamResource
Expert view
Expert from Word to the Wise responds by stating that failing to meet the authentication requirements can cause email providers to identify a message as spam. Proper authentication is essential for optimal inbox placement.
17 Jul 2021 - Word to the Wise
What the documentation says
4 technical articles
Gmail's failure to verify authenticated emails often arises from issues within SPF, DKIM, and DMARC configurations. Incorrect, missing, or syntactically flawed SPF records prevent proper sender authorization. Improper DKIM configurations, like key length or selector problems, lead to verification failures. Finally, a DMARC policy set to reject or quarantine emails failing SPF/DKIM will cause Gmail to report verification issues.
Key findings
- SPF Issues: Incorrect or missing SPF records, including syntax errors, prevent Gmail from verifying authorized senders.
- DKIM Misconfiguration: Improper DKIM setup, specifically with key length or selector issues, causes emails to fail verification checks.
- DMARC Policy Enforcement: DMARC policies set to reject or quarantine emails that fail SPF and DKIM cause Gmail to report verification problems.
Key considerations
- Validate SPF Records: Ensure your SPF record is present, accurate, and lists all authorized sending sources for your domain, checking for any syntax errors.
- Check DKIM Configuration: Verify that your DKIM setup is correct, paying particular attention to key lengths and selector configurations.
- Review DMARC Policy: Understand and carefully configure your DMARC policy, considering the impact of reject or quarantine settings on deliverability.
Technical article
Documentation from RFC responds by stating that even a minor syntax error in your SPF record (e.g., a typo, incorrect character) can invalidate it and cause authentication failures. Always double-check your SPF record for errors.
23 May 2023 - RFC
Technical article
Documentation from DMARC.org responds by stating that Domain-based Message Authentication, Reporting & Conformance (DMARC) builds upon SPF and DKIM. If your DMARC policy is set to reject or quarantine emails that fail SPF and DKIM checks, Gmail will likely report a verification issue.
8 Jun 2023 - DMARC.org
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