SPF Flattening the Safe Way: Avoiding DNS and Deliverability Issues

November 27, 2025 • InboxGreenEmail Team

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SPF Flattening the Safe Way: Avoiding DNS and Deliverability Issues

As a SaaS founder or marketer, you know that email deliverability is crucial. If your emails land in spam folders, your carefully crafted messages go unseen. One common issue that can affect deliverability is the way you configure your SPF records. In this article, we will dive into SPF flattening, a technique that can simplify your SPF records. However, we will also discuss how to do it safely to avoid DNS and deliverability issues.

Understanding SPF and Its Importance

Sender Policy Framework (SPF) is an email authentication method that helps prevent spoofing. It allows you to specify which mail servers are permitted to send email on behalf of your domain. A correctly configured SPF record can enhance your email reputation and improve inbox placement. However, when your SPF record becomes too complex, it can lead to problems.

The Problem with Complex SPF Records

When your SPF record includes too many DNS lookups, you risk hitting the 10 DNS lookup limit imposed by the SPF specification. Exceeding this limit can cause your SPF record to fail, leading to deliverability issues. This is where SPF flattening comes into play.

What is SPF Flattening?

SPF flattening is the process of simplifying your SPF record by replacing mechanisms that require DNS lookups with their corresponding IP addresses. This can help you stay within the lookup limit while maintaining a valid SPF record. However, it is essential to do this carefully to avoid introducing new issues.

Step-by-Step Guide to SPF Flattening

Step 1: Analyze Your Current SPF Record

Before you start flattening, you need to know what your current SPF record looks like. Use the InboxGreen checker to analyze your SPF record. This tool will show you how many DNS lookups your record currently requires and identify any potential issues.

v=spf1 include:example.com include:anotherexample.com -all

In this example, the record includes two mechanisms that will require DNS lookups. You need to find out what IP addresses these mechanisms resolve to.

Step 2: Resolve Included Domains

Next, resolve the included domains to their respective IP addresses. You can use command-line tools like dig or online DNS lookup tools to find the IP addresses. For example:

dig example.com

This command will return the IP addresses associated with example.com. Make sure to document these addresses for the next step.

Step 3: Create a New Flattened SPF Record

Once you have all the necessary IP addresses, you can create a new SPF record that replaces the included domains with their corresponding IPs. For example, if example.com resolves to 192.0.2.1 and anotherexample.com resolves to 198.51.100.1, your new SPF record would look like this:

v=spf1 ip4:192.0.2.1 ip4:198.51.100.1 -all

This record is now simpler and should not exceed the DNS lookup limit.

Step 4: Test Your New SPF Record

Before making any changes live, test your new SPF record using the InboxGreen checker. This tool will help you ensure that your new record is valid and properly formatted. It will also show you how many DNS lookups it requires.

Step 5: Update Your DNS Records

If your new SPF record passes the test, it is time to update your DNS records. Log in to your DNS provider and replace the old SPF record with the new one. Make sure to allow some time for DNS propagation, which can take up to 48 hours.

Step 6: Monitor Deliverability

After updating your SPF record, keep an eye on your email deliverability. Use tools like InboxGreen's checker to monitor your inbox placement. If you notice any issues, revisit your SPF record and make adjustments as necessary.

Common Gotchas to Avoid

  • Ignoring DNS Propagation: Changes to DNS records can take time to propagate. Be patient and monitor your email deliverability during this period.
  • Overlooking Other Authentication Methods: SPF is just one part of the email authentication puzzle. Ensure that you have DKIM and DMARC set up correctly as well.
  • Not Testing Thoroughly: Always test your new SPF record before going live. A small mistake can lead to significant deliverability issues.

Conclusion: What to Do Next

SPF flattening can be an effective way to simplify your SPF records and improve email deliverability. By following the steps outlined above, you can avoid common pitfalls and ensure that your emails reach the inbox.

Now that you have a better understanding of SPF flattening, it’s time to take action. Use the InboxGreen checker to analyze your current SPF record. If you need help generating a new SPF record, check out our SPF generator. For a comprehensive email authentication strategy, consider using our DMARC generator as well.

Remember, email deliverability is a continuous process. Regularly monitor your records and make adjustments as needed. Happy emailing!

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