Understanding Multiple SPF Records: Best Practices For Domain Email Security

In today's digital landscape, email security is paramount due to rising threats like phishing and spoofing. A key component of email protection is the Sender Policy Framework (SPF), which verifies the legitimacy of email sources from a domain. However, managing multiple SPF records can lead to authentication problems that hinder email deliverability. This guide will cover SPF records, the complications of having multiple entries, and best practices for maintaining robust domain email security. For more details, kindly visit the Autospf website.

What Are SPF Records?

SPF records are TXT entries in your domain's DNS that identify authorized mail servers for sending emails on your behalf. When an email is received, the server consults the SPF record to confirm the sender's authenticity. Emails from unauthorized sources may be marked as spam or rejected.

Here’s an example of a simple SPF record:

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

In this example:

• v=spf1 specifies the SPF version.


• include:_spf.google.com authorizes Google’s mail servers to send emails for the domain.


• ~all indicates a soft fail for unauthorized senders.

Can You Have Multiple SPF Records?

In brief, the answer is negative. According to DNS specifications, a domain can contain only a single SPF record. Including multiple SPF records for the same domain contravenes DNS regulations and results in a PermError, hindering email servers from accurately verifying emails from your domain.

Common Reasons for Multiple SPF Records

• Using multiple email services, such as marketing platforms, customer relationship management, and cloud-based email services.


• Miscommunication between teams managing DNS and email systems.


• Adding new services without consolidating SPF entries.

Problems with Multiple SPF Records

• Authentication Failures: Email servers are unable to interpret multiple SPF records, resulting in a PermError that prevents the successful delivery of legitimate emails.


• Inconsistent Deliverability: Receiving servers might classify emails as spam or refuse them, which can negatively impact your domain's sender reputation.


• Vulnerability to Spoofing: Improperly configured SPF settings can expose your domain to the risk of being impersonated by unauthorized senders. 

Best Practices for Managing SPF Records

To avoid issues associated with multiple SPF records, follow these best practices:

• Consolidate Your SPF Records: Rather than generating several SPF records, it is advisable to combine all approved senders into one comprehensive SPF record. For instance:

If you use Google Workspace and Mailchimp, consolidate their entries:

This ensures that all authorized services are included in one record.

• Use the Include Mechanism: The inclusion mechanism allows you to grant authorization to external services by citing their SPF records. Generally, each service provider will provide the specific SPF entry that should be incorporated into your own record. For example:


• Google Workspace: include:_spf.google.com


• Microsoft 365: include:spf.protection.outlook.com

Ensure you review each service’s documentation for accurate entries.

• Stay Within the 10-DNS Lookup Limit: SPF imposes a restriction of 10 DNS lookups, indicating that the server receiving the email is permitted to conduct a maximum of 10 DNS queries for SPF record validation. If this threshold is surpassed, an error will occur. To ensure compliance with this limitation:


• Remove unused or outdated services from your SPF record.


• Use subdomains for specific services if your main domain’s SPF record exceeds the limit.


• Use DNS flattening tools to reduce unnecessary lookups.


• Regularly Audit Your SPF Record: Regularly assess your SPF record to verify that it accurately represents only the current and essential email services. Eliminate any obsolete entries and ensure that the SPF record aligns with the most recent configurations of the services you utilize.







• Test Your SPF Record: After updating your SPF record, it's recommended to use tools like MXToolbox or the Kitterman SPF Validator to check its accuracy and functionality. These tests ensure your SPF record is working correctly and that your emails are properly authenticated.


• Consider Using a Third-Party SPF Management Tool: In complex email environments, third-party solutions such as SPF flatteners and email authentication platforms can streamline SPF management. They enhance DNS lookups and maintain compliance of your SPF record.


• Implement Additional Email Security Protocols: While SPF is a crucial layer of email security, it works best when combined with other protocols:


• DKIM (DomainKeys Identified Mail): Adds a digital signature to your emails to verify their authenticity.


• DMARC (Domain-based Message Authentication, Reporting, and Conformance): Aligns SPF and DKIM to enforce stricter email authentication policies and provides actionable reports.

Together, these protocols offer comprehensive protection against spoofing and phishing attacks.