Summary
The 'Gmail sender unauthenticated' alert indicates email authentication problems, typically due to failures in SPF and DKIM checks. Key factors include misconfigured or missing SPF, DKIM, and DMARC records, alignment issues between the 'Header From' domain and SPF/DKIM domains, and ensuring that all sending sources (including ESPs) are correctly included in SPF records. Resolving the issue involves properly setting up and validating these authentication methods, verifying DKIM signatures, and monitoring authentication reports. Furthermore, proper authentication helps with sender branding and building trust with recipients.
Key findings
- SPF/DKIM Failure: Emails failing SPF and DKIM checks trigger the 'sender unauthenticated' alert.
- Alignment Issues: Misalignment between the 'Header From' domain and domains used for SPF/DKIM contributes to the alert.
- SPF/DKIM/DMARC Importance: Correct setup and validation of SPF, DKIM, and DMARC are critical for resolving authentication issues.
- ESP Configuration: Ensure SPF records include ESP servers when using an Email Service Provider.
- Branding and Trust: Proper email authentication helps build trust and brand recognition with Gmail users.
Key considerations
- Check Auth-Results: Examine the auth-results header to identify specific authentication failures.
- Record Validation: Regularly validate SPF, DKIM, and DMARC records to ensure correct configuration.
- Complete SPF Records: Ensure that all sending sources are included in the SPF record.
- Monitor DMARC Reports: Actively monitor DMARC reports to identify and address authentication issues.
- Correct DKIM Implementation: Ensure the DKIM signing process is correctly implemented on the sending server.
- Avoid strict settings: Ensure aspf and adkim are not set to strict.
What email marketers say
9 marketer opinions
The 'Gmail sender unauthenticated' alert arises from issues with email authentication, primarily SPF, DKIM, and DMARC. Misconfigurations, missing records, or alignment problems between the 'Header From' domain and authentication domains are common causes. Resolving the issue involves ensuring correct setup and validation of SPF, DKIM, and DMARC records, including all sending sources and ESP servers. The goal is to prove email legitimacy and prevent spam classifications.
Key opinions
- SPF/DKIM Failure: The primary cause is failure to pass SPF or DKIM checks due to misconfiguration or missing records.
- Authentication Alignment: Alignment issues between the 'Header From' domain and SPF/DKIM domains can trigger the alert.
- DMARC Importance: Implementing DMARC alongside SPF and DKIM is crucial for comprehensive authentication.
- ESP Inclusion: When using an Email Service Provider (ESP), ensure their servers are included in your SPF record.
- Missing DKIM Signature: A missing or improperly implemented DKIM signature can cause authentication failures.
- Strict settings: Check the aspf and adkim settings
Key considerations
- Record Validation: Regularly validate SPF, DKIM, and DMARC records using online tools to ensure correct syntax and functionality.
- Source Inclusion: Ensure that all sending sources, including ESPs and internal servers, are included in your SPF record.
- Gradual DMARC Policy: Implement DMARC with a gradual policy, starting with 'p=none' to monitor email flows before enforcing stricter policies.
- DKIM Implementation: Confirm the DKIM signing process is correctly implemented on the sending server.
- ESP Configuration: Carefully configure SPF and DKIM settings within your ESP to align with your domain.
- Monitor Authentication Reports: Actively monitor DMARC reports to identify and address any authentication issues.
Marketer view
Email marketer from StackOverflow mentioned that a missing DKIM signature can also trigger the 'sender is unauthenticated' warning. The user suggests confirming that the DKIM signing process is correctly implemented on the sending server.
8 Apr 2023 - StackOverflow
Marketer view
Email marketer from Mailjet explains that the 'sender is unauthenticated' warning in Gmail means your emails might not be passing SPF or DKIM checks. To fix this, ensure you've properly configured SPF and DKIM records for your sending domain and that they are validated.
20 Nov 2023 - Mailjet
What the experts say
3 expert opinions
The 'Gmail sender unauthenticated' alert is triggered by issues related to email authentication, specifically SPF and DKIM. A primary cause is the failure of alignment checks between the 'Header From' domain and the domains used for SPF and DKIM. Proper configuration of SPF and DKIM, ensuring that all sending sources are accurately listed in the SPF record and that DKIM signatures are valid and aligned, is essential for resolving the alert. Additionally, the alert serves to help Gmail users identify legitimate senders, improving sender branding and trust.
Key opinions
- Authentication Alignment Failure: Failure of alignment checks between the 'Header From' domain and domains used for SPF/DKIM is a primary cause.
- SPF/DKIM Misconfiguration: Missing or misconfigured SPF and DKIM records are common reasons for the alert.
- Branding and Trust: Proper authentication helps associate branding with emails, building trust and helping users identify legitimate senders.
Key considerations
- Check Auth-Results Header: Review the auth-results header to diagnose authentication failures.
- Valid SPF Records: Ensure the SPF record accurately lists all authorized sending sources.
- Valid DKIM Signatures: Verify that DKIM signatures are valid and correctly aligned.
Expert view
Expert from Word to the Wise, Laura Atkins, answers that the 'unauthenticated sender' notification isn't necessarily about deliverability but about helping Gmail users identify legitimate senders. She explains that ensuring proper SPF and DKIM setup helps associate your branding with your emails and build trust with Gmail recipients, preventing the alert.
9 Apr 2024 - Word to the Wise
Expert view
Expert from Email Geeks explains that the Gmail alert likely means the email is not aligned authenticated and suggests checking the auth-results header.
18 May 2024 - Email Geeks
What the documentation says
5 technical articles
The 'Gmail sender unauthenticated' message arises when emails fail SPF or DKIM checks, indicating a potential issue with email authentication. SPF, DKIM, and DMARC are key protocols designed to prevent email spoofing by verifying sender authenticity. SPF verifies the sending server's authorization, DKIM provides a digital signature for message integrity, and DMARC builds upon SPF and DKIM to offer domain owners control over unauthorized email use. Proper setup of these protocols is crucial to resolve authentication issues and ensure legitimate emails are delivered.
Key findings
- SPF/DKIM Failure: The 'sender is unauthenticated' message occurs when emails fail SPF or DKIM checks.
- SPF Purpose: SPF is designed to prevent spammers from forging 'from' addresses by verifying the sending server's authorization.
- DKIM Purpose: DKIM provides a digital signature, allowing recipients to verify the message's authenticity and integrity.
- DMARC Purpose: DMARC protects domains from unauthorized use and email spoofing by building on SPF and DKIM.
- Overall: The combined protocols of SPF, DKIM and DMARC help email providers to verify the source of an email.
Key considerations
- Proper Setup: Ensure proper setup of SPF, DKIM, and DMARC records to resolve authentication issues.
- Record Validation: Regularly validate SPF, DKIM, and DMARC records to ensure they are correctly configured.
- Spoof Prevention: Utilize SPF, DKIM, and DMARC to prevent email spoofing and unauthorized use of your domain.
- Verify Authentication: Always verify authentication to ensure that mail is being sent from the source you expect.
Technical article
Documentation from Microsoft responds that they have been using email authentication for over a decade to verify the sender of an email message isn't forged, and that the source IP address of the sending server is authorized to send mail for the sending domain.
30 Mar 2022 - Microsoft
Technical article
Documentation from Google Workspace Admin Help explains that a 'sender is unauthenticated' message typically occurs when a message fails SPF or DKIM checks. Resolving this involves ensuring proper SPF, DKIM, and DMARC setup.
29 Nov 2022 - Google Workspace Admin Help
