SPF Too Many DNS Lookups: How to Reduce Includes Safely

November 22, 2025 • InboxGreenEmail Team

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SPF Too Many DNS Lookups: How to Reduce Includes Safely

As a SaaS founder or marketer, you know the importance of getting your emails delivered to the inbox. One common pitfall that can hinder your email deliverability is the dreaded "too many DNS lookups" error in your SPF record. This issue can prevent your emails from being authenticated properly, leading to poor inbox placement. But don’t worry, we’ll walk through how to diagnose and fix it without losing your mind.

Understanding the SPF Lookup Limit

SPF, or Sender Policy Framework, is a protocol that helps email servers verify that an email comes from an authorized sender. However, SPF records have a limit: you can only have 10 DNS lookups per SPF check. This includes any include: statements, a: records, mx: records, and more. If you exceed this limit, your SPF record will fail, and your emails may be marked as spam.

Diagnosing the Problem

First, you need to check your current SPF record. You can do this using the InboxGreen checker. Just enter your domain, and it will show you your SPF record along with any issues. Look for the number of DNS lookups. If you see a warning about exceeding the limit, it’s time to take action.

Identifying Your Includes

Once you have your SPF record, take a close look at the include: statements. These are often the culprits when it comes to excessive DNS lookups. For example, your SPF record might look something like this:

v=spf1 include:spf.protection.outlook.com include:_spf.google.com include:mailgun.org -all

In this case, you have three includes, which already counts as three lookups. If you have more includes or additional mechanisms, you can quickly hit that 10 lookup limit.

Reducing Your Includes

Here are some practical steps to reduce your SPF includes:

  • Consolidate Services: Check if any of your email service providers offer combined services. For instance, if you are using multiple services for transactional and marketing emails, see if you can migrate to a single provider.
  • Use Subdomains: If you have multiple brands or services, consider using subdomains for different email streams. Each subdomain can have its own SPF record, allowing you to distribute the DNS lookups.
  • Remove Unused Includes: Regularly audit your SPF record. If you have not used a service in a while, remove its include statement. Every little bit helps.
  • Use IP Addresses: If you have static IP addresses for your sending servers, you can include them directly in your SPF record. This avoids additional DNS lookups. For example:
v=spf1 ip4:192.0.2.1 ip4:198.51.100.1 -all

This counts as one lookup, regardless of how many IPs you include.

Testing Your Changes

After making your changes, it’s crucial to test your new SPF record. Use the InboxGreen checker again to ensure you are within the lookup limit and that the record is valid. If everything checks out, you can move on to the next step.

Implementing DKIM and DMARC

While fixing your SPF record is essential, don’t forget about DKIM and DMARC. These protocols work in tandem with SPF to improve your email deliverability. DKIM adds a digital signature to your emails, while DMARC helps you manage how your domain handles unauthenticated emails.

Set up DKIM by generating the necessary keys through your email service provider. Most providers have straightforward instructions for this. For DMARC, you can use the DMARC generator to create a policy that suits your needs. Here’s a simple DMARC record:

v=DMARC1; p=none; rua=mailto:[email protected]

This record tells receiving servers to send DMARC reports to your specified email address without enforcing any actions on failed emails.

What to Do Next

Now that you have a better understanding of SPF lookups and how to manage them, take action. Start by checking your SPF record with the InboxGreen checker. Make the necessary adjustments, and don’t forget to implement DKIM and DMARC for added security.

For more advanced users, consider using the InboxGreen API to automate your email authentication processes. And if you need help with pricing, check out our pricing page for more information.

Remember, maintaining a clean SPF record is crucial for your email deliverability. Take the time to audit your records regularly, and you’ll see the benefits in your inbox placement.

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