How To Resolve SPF Permerror & Improve
Email Deliverability


The Sender Policy Framework (SPF) is an essential protocol for authenticating emails, designed to combat email spoofing and to verify that messages originating from your domain are deemed legitimate by the servers receiving them. Nevertheless, improper SPF configurations can result in issues like SPF PermError, which can adversely affect your email deliverability, potentially leading to your messages being rejected or classified as spam.

This guide will provide an overview of SPF PermError, outline its typical causes, and offer best practices for resolving this issue while enhancing your overall email authentication strategy. Learn more by visiting this link.


What Is SPF PermError?


A Permanent Error (PermError) related to SPF arises when the mail server receiving your message is unable to accurately interpret your SPF record, rendering it ineffective. This situation causes your email to fail SPF validation, potentially leading to issues such as bounced emails, being marked as spam, or outright rejection by major email providers like Gmail, Outlook, and Yahoo.


Common Causes of SPF PermError:

  • Multiple SPF Records: Possessing multiple SPF TXT records within your DNS settings.

  • Exceeding the 10-DNS Lookup Limit: SPF permits a maximum of 10 DNS queries.

  • Syntax Errors: The SPF record may have improper formatting or lack necessary parameters.

  • Deprecated SPF Mechanisms: Employing obsolete SPF methods such as ptr.

  • Too Many “Include” Statements: Incorporating various external email service providers.


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How to Fix SPF PermError


1. Ensure You Have Only One SPF Record

Numerous problems with SPF occur when a domain contains several SPF records, leading to the failure of SPF authentication. To verify your SPF records, utilize an SPF lookup tool like:

  • MXToolBox SPF Checker

  • Google Admin Toolbox Check MX

If multiple SPF records exist, merge them into a single valid SPF record.

Example of Incorrect SPF Configuration (Multiple Records):

v=spf1 include:_spf.google.com ~all

v=spf1 include:_spf.mailgun.org -all

Corrected SPF Record (Merged Into One):

v=spf1 include:_spf.google.com include:_spf.mailgun.org ~all


2. Reduce DNS Lookups to Stay Under the 10-Limit Rule

SPF permits up to 10 DNS queries. Surpassing this limit will result in an automatic failure of your SPF record, leading to an SPF PermError.

To reduce lookups:

  • Remove unnecessary include statements.

  • Replace multiple includes with a single custom SPF record.

  • Use IP addresses instead of domain-based lookups when possible.

Example of Excessive DNS Lookups (Incorrect):

v=spf1 include:_spf.google.com include:_spf.mailgun.org include:_spf.sendgrid.net include:_spf.mandrillapp.com include:_spf.salesforce.com ~all

Optimized SPF Record (Corrected Version):

v=spf1 ip4:192.168.1.1 ip4:203.0.113.0/24 include:_spf.google.com ~all


3. Remove Deprecated or Unnecessary Mechanisms

Certain SPF mechanisms have become obsolete or unnecessary, resulting in failures in authentication. For example, the ptr mechanism is now discouraged.

Example of Incorrect SPF Syntax (Using Deprecated ptr):

v=spf1 ptr include:_spf.google.com ~all

Corrected SPF Record (Without ptr):

v=spf1 include:_spf.google.com ~all



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4. Use SPF Macros and Flattening to Reduce Lookups

If your SPF record includes too many external services, SPF flattening can help reduce lookups.

  • Use tools like OpenSPF or PowerSPF to generate a flattened SPF record.

  • Use redirect= instead of multiple include statements for better efficiency.

Example Using Redirect for Simplification:

v=spf1 redirect=_spf.example.com

This points to a single SPF record that contains all necessary includes, preventing excessive lookups.


Additional Best Practices to Improve Email Deliverability


Implement DKIM & DMARC Alongside SPF

Although SPF is useful for verifying sender identity, integrating it with DKIM (DomainKeys Identified Mail) and DMARC (Domain-based Message Authentication, Reporting, and Conformance) greatly enhances both the security and deliverability of your emails.

Example of a DMARC Record:

v=DMARC1; p=quarantine; rua=mailto:dmarc-reports@example.com; ruf=mailto:forensic-reports@example.com; pct=100;


Regularly Monitor Your SPF Record

As email service providers often revise their SPF include records, it is essential to keep an eye on and refresh your SPF record on a regular basis.

  • Set up DMARC reports to track authentication failures.

  • Review logs in Google Postmaster Tools or Microsoft Defender for Office 365.

Use a Dedicated Sending IP Address

To minimize the chances of being blacklisted and enhance your domain's reputation, consider utilizing a dedicated IP rather than relying on shared email servers.