For businesses that depend on email for communication, ensuring the security and deliverability of messages is vital. A key component of this security is the Sender Policy Framework (SPF) record, which helps prevent email spoofing by verifying authorized IP addresses for sending emails from your domain. However, managing SPF records can be complicated due to the 10 DNS lookup limit imposed by SPF. SPF flattening provides a solution by optimizing these records for enhanced security and deliverability. This guide delves into the concept of SPF flattening, its significance, and its benefits for your email infrastructure.

What is SPF and Why Does It Matter?

SPF, or Sender Policy Framework, is an email authentication method designed to stop unauthorized entities from sending emails that appear to originate from your domain. It achieves this by defining which IP addresses can send emails on your behalf, thereby safeguarding your domain's reputation and minimizing the risk of harmful emails reaching recipients.

However, SPF records are limited to a maximum of 10 DNS lookups; exceeding this limit can lead to SPF failures, resulting in legitimate messages being categorized as spam or rejected. As businesses expand and utilize various email services, hitting this lookup cap often becomes a challenge that affects both email deliverability and security.

Understanding SPF Flattening

SPF flattening is a method that streamlines SPF records by consolidating all required IP addresses into one list, rather than using multiple include statements to reference external domains. This technique reduces the number of DNS lookups, helping to maintain compliance with the 10-lookup limit and enhancing performance.

How SPF Flattening Works

• Identify Included Domains: Initially, the SPF record identifies all domains specified in the include statements. These usually refer to third-party email services or authorized IP addresses permitted to send emails on your behalf.


• Retrieve IP Addresses: Each domain listed in the include statement conducts a DNS lookup to obtain IP addresses. SPF flattening consolidates these IPs into your SPF record, removing the necessity for separate lookups.


• Create a Flat SPF Record: Directly listing all IP addresses in your SPF record simplifies it, minimizes DNS lookups, and enhances email performance.

Benefits of SPF Flattening

• Improved Deliverability: Exceeding the 10-lookup limit in your SPF record can lead to email delivery issues. By flattening your SPF record, you can stay within this limit and enhance the likelihood of successful email delivery without being marked as spam or bounced.


• Enhanced Security: A properly optimized SPF record enhances your domain's protection against spoofing and phishing threats. Simplified SPF records improve clarity and precision, minimizing the risk of unauthorized email sending on your behalf.


• Simplified Maintenance: A flat SPF record streamlines management and updates by consolidating IP addresses into one list, eliminating the need to monitor multiple include statements and domains. This approach is advantageous for organizations that frequently modify or expand their email services.


• Reduced DNS Lookup Time: Flattened SPF records enhance the speed at which DNS servers handle your SPF record, resulting in quicker and more efficient email validation. This advancement optimizes email authentication for both senders and receivers.


• Compliance with Email Providers: Numerous email services implement SPF checks, with some imposing consequences for emails that do not pass validation. Flattening your SPF record enhances compliance, thereby improving the chances of your emails being delivered to inboxes instead of landing in spam folders.

How to Implement SPF Flattening for Your Domain

Step 1: Identify Third-Party Services

Examine your existing SPF record and identify all the include directives. These usually relate to external email services, including marketing platforms, customer relationship management (CRM) systems, or various other email service providers.

Step 2: Resolve DNS Records

Conduct DNS queries for every domain specified in your include statements to obtain their corresponding IP addresses. Various online resources and SPF record generators are available to facilitate this task, offering a structured compilation of IP addresses linked to each domain.

Step 3: Consolidate IP Addresses

Create a new SPF record by listing the IP addresses directly instead of using “include” statements. For example, instead of writing include:mailservice.com, list the IP addresses provided by the service directly in your SPF record.

Step 4: Regularly Review and Update

Since third-party providers can update their IP addresses, it’s essential to periodically review and update your SPF record to keep it accurate. Some organizations use automated tools that monitor changes in third-party SPF records and suggest updates to ensure continued compliance. Explore further information at www.autospf.com.