Summary
SPF failures, even when the sending IP seems to be included in the SPF record, can result from several factors. Common culprits include checking the SPF record for the wrong domain (it should be the MAIL FROM domain), syntax errors or exceeding DNS lookup limits within the SPF record, delays in DNS propagation after updates, incorrect or outdated IP addresses, conflicts with DMARC policies, use of the 'ptr' mechanism, having multiple SPF records, or encountering PermErrors. Authentication issues such as incomplete SPF records, DMARC misalignment, or broken DKIM records also contribute, as does the use of a hard fail policy.
Key findings
- Incorrect Domain: The SPF check must be performed against the domain used in the MAIL FROM (Return-Path) address, not the From: header.
- SPF Syntax and Lookups: Syntax errors, exceeding the 10 DNS lookup limit, and issues with 'include:' mechanisms can cause failures.
- DNS Propagation: Changes to SPF records can take up to 48 hours to propagate across the internet.
- IP Address Mismatch: The IP address in the SPF record must match the sending server's IP address.
- DMARC Conflicts: DMARC policies set to reject or quarantine will cause emails to be blocked if SPF fails.
- PTR Mechanism Issues: The 'ptr' mechanism can cause unpredictable SPF results due to reliance on reverse DNS lookups.
- Multiple SPF Records: Having more than one SPF record for a domain is invalid and can cause issues.
- PermError: Indicates there is something fundamentally wrong in the SPF record itself
- Hard Fail: The IP being used is explicitley forbidden
- Authentication Problems: Incomplete records, or broken authentication set ups
Key considerations
- Check the MAIL FROM Domain: Always verify the SPF record of the domain used in the MAIL FROM (Return-Path) address.
- Validate SPF Syntax: Use SPF record validators to check for syntax errors and exceeding the DNS lookup limit.
- Allow DNS Propagation Time: Allow sufficient time for DNS changes to propagate after updating the SPF record.
- Monitor DMARC Reports: Regularly review DMARC reports to identify and address SPF alignment issues.
- Simplify SPF Records: Consider flattening SPF records to reduce DNS lookups.
- Avoid PTR Mechanism: Discourage using the PTR mechanism.
- Single SPF Record: Ensure that a single, valid SPF record is set for each domain.
- Troubleshoot PermError: Investigate and resolve any 'PermError' issues in the SPF record to ensure proper evaluation.
- Address hard Fails: Investigate why the IP used is not permitted
- Validate Authentication Set up: Ensure the SPF records are valid and complete
What email marketers say
9 marketer opinions
SPF failures, even when the sending IP appears to be included in the SPF record, can stem from a variety of issues. The most common reasons include checking the SPF record of the wrong domain (it should be the domain used in the MAIL FROM address), syntax errors or exceeding DNS lookup limits in the SPF record, DNS propagation delays after making changes, incorrect or outdated IP addresses, conflicts with DMARC policies, using the 'ptr' mechanism, having multiple SPF records, or encountering PermErrors.
Key opinions
- Wrong Domain: SPF checks are performed against the MAIL FROM domain, not the From: header domain. Verify you're checking the correct SPF record.
- Syntax and Lookup Limits: Syntax errors, exceeding the 10 DNS lookup limit, or incorrect use of 'include:' or 'a:' mechanisms can cause failures.
- Propagation Delays: DNS changes may take up to 48 hours to propagate, leading to temporary SPF failures.
- Incorrect IP Address: Ensure the IP address in the SPF record matches the sending server's current IP address.
- DMARC Conflicts: If DMARC is set to reject/quarantine, SPF failures will cause emails to be blocked.
- PTR Mechanism Issues: The 'ptr' mechanism can lead to unpredictable results and failures due to reliance on reverse DNS.
- Multiple SPF Records: Having more than one SPF record for a domain is invalid and can cause issues.
Key considerations
- Check MAIL FROM: Always verify the SPF record of the domain used in the MAIL FROM (Return-Path) address.
- Validate Syntax: Use SPF record validators to check for syntax errors and exceeding the DNS lookup limit.
- Allow Time for Propagation: After making changes to your SPF record, allow sufficient time for DNS propagation.
- Monitor DMARC Reports: Regularly review DMARC reports to identify and address SPF alignment issues.
- Simplify SPF Records: Consider flattening SPF records to reduce DNS lookups and improve performance.
- Avoid PTR: Avoid the use of 'ptr' mechanism because of its unpredictability and possible negative results.
- Single SPF record: Ensure there is only one SPF record per domain
Marketer view
Email marketer from EasyDMARC shares that if the IP address listed in your SPF record is incorrect, outdated, or doesn't match the sending server's IP, SPF will fail.
3 Oct 2022 - EasyDMARC
Marketer view
Email marketer from AuthSMTP explains that there might be a conflict with other email authentication methods (DKIM, DMARC). If DMARC policy is set to reject or quarantine and SPF fails, the email might be blocked.
7 Mar 2022 - AuthSMTP
What the experts say
6 expert opinions
SPF failures, even with the sending IP seemingly in the record, can be caused by a multitude of issues. These include an incomplete SPF record lacking the sending IP, DMARC failures due to domain misalignment (the domain in the From: header not matching those in the SPF or DKIM records), general authentication setup issues (like a broken DKIM record), or a 'PermError' indicating a problem evaluating the SPF record. An SPF hard fail means the sender is explicitly not authorized, leading to message rejection.
Key opinions
- Incomplete SPF Record: The SPF record may not contain the specific IP address used for sending, leading to SPF failure.
- DMARC Misalignment: DMARC requires the domain in the From: header to align with domains in the SPF or DKIM records; misalignment leads to DMARC failure.
- Broken Authentication: Issues like a broken DKIM record can contribute to overall authentication failures.
- SPF PermError: A 'PermError' indicates an issue in the SPF record preventing proper evaluation.
- SPF Hard Fail: An SPF hard fail indicates the sender is explicitly not authorized and the receiving server should reject the message.
Key considerations
- Verify SPF Record: Ensure the SPF record is complete and contains all authorized sending IP addresses.
- Address DMARC Alignment: Ensure proper alignment between the From: domain and SPF/DKIM domains to achieve DMARC pass.
- Check Authentication Setup: Thoroughly check all aspects of email authentication setup, including SPF, DKIM, and DMARC.
- Troubleshoot SPF PermError: Investigate and resolve any 'PermError' issues in the SPF record to ensure proper evaluation.
- Address Hard Fails: If you're getting SPF hard fails, investigate why the IP being used is not permitted.
Expert view
Expert from Spam Resource explains that an SPF hard fail indicates that the sender is explicitly not authorized to send email on behalf of the domain. It means that the IP address used to send the email does not match any of the IP addresses or ranges listed in the SPF record, and the SPF record ends with '-all' or '-redirect'. This tells receiving mail servers to reject messages that fail the SPF check.
13 May 2025 - Spam Resource
Expert view
Expert from Email Geeks explains many things are broken in authentication setup. SPF for email.phone2action.com only has one IP and it's not 167.89.79.130. DKIM for phone2action.com looks okay in DNS but failed the test. The sender domain (Peta.org) is not authenticated and failing DMARC.
24 Jan 2022 - Email Geeks
What the documentation says
5 technical articles
SPF failures, even when an IP address seems to be included, arise from various technical issues. Key causes include the sending IP not being authorized in the SPF record of the MAIL FROM domain, syntax errors (typos, incorrect mechanisms, exceeding TXT record limits), problems with 'include:' mechanisms (errors in included domains, exceeding the 10 DNS lookup limit), and general configuration errors as highlighted by Microsoft and Google. Essentially, the SPF evaluation process is strict, and even small errors can lead to failures.
Key findings
- Authorization Failure: If the sending IP is not explicitly listed as an authorized sender in the SPF record for the MAIL FROM domain, the check fails.
- Syntax Errors: Typos, misuse of SPF mechanisms, or exceeding DNS TXT record limits invalidate the SPF record.
- Include Issues: Problems in included domains or exceeding the 10 DNS lookup limit due to nested 'include:' statements cause failure.
- Configuration Errors: Incorrect syntax and incorrect include statements of 3rd party senders
Key considerations
- Verify Authorization: Confirm the sending server's IP address is explicitly authorized in the correct SPF record.
- Check Syntax Carefully: Thoroughly validate the SPF record for syntax errors, typos, and adherence to DNS limits.
- Manage Includes: Carefully manage 'include:' mechanisms, ensure included domains have valid SPF records, and avoid exceeding DNS lookup limits.
- Thorough Configuration: Ensure you are validating all aspects of the SPF setup and configuration.
Technical article
Documentation from Google explains how to configure SPF records for Google Workspace and lists potential causes for SPF failures, including incorrect syntax, missing include statements for third-party senders, and DNS propagation delays.
9 Nov 2024 - Google
Technical article
Documentation from Valimail explains that if your SPF record relies on 'include:' mechanisms, but the included domains have errors or invalid SPF records, your SPF check might fail. It also explains exceeding the 10 DNS lookup limit is a common issue if too many includes are present.
8 Nov 2021 - Valimail
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