In the current digital landscape, safeguarding email communications is crucial for companies to defend their domains against harmful threats and maintain secure interactions. A vital tool in this effort is the Sender Policy Framework (SPF), which verifies that emails are sent from permitted servers, thus minimizing the chances of phishing and spam attacks. Nevertheless, handling SPF records can become quite intricate, particularly as they expand due to dependencies on external services. 

SPF flattening presents an effective approach to streamline and enhance these records, leading to improved security and performance. This article will examine SPF flattening in detail and provide insights on how to simplify your SPF records.

What Is SPF Flattening?

SPF Flattening is streamlining the Sender Policy Framework (SPF) record to minimize the DNS lookups needed for verifying email senders. SPF records enable domain owners to designate which mail servers have permission to send emails on their behalf. These records include a compilation of IP addresses and domains permitted to dispatch emails.

SPF records can sometimes grow extensive and intricate, particularly when a domain incorporates various third-party services, such as email marketing tools or cloud services, which need to be part of the SPF configuration. Each time an SPF record references another domain or subdomain, it necessitates an extra DNS lookup for validation. When an SPF record has an excessive number of DNS lookups, it may cause the SPF check to fail, resulting in problems with email delivery.

Why SPF Flattening Matters

There are several important reasons why SPF flattening is essential:

• DNS Lookup Restrictions: SPF records have a maximum allowance of 10 DNS lookups. Surpassing this limit may lead to SPF failures, causing emails to be rejected or classified as spam.


• Safety: Streamlined records minimize the chances of misconfigurations and potential vulnerabilities that may result from overly intricate SPF records.

How SPF Flattening Works

Flattening an SPF record consists of multiple stages:

1. Identify SPF Includes

The initial phase of simplifying an SPF record involves recognizing all the include mechanisms present within it. These mechanisms point to additional SPF records associated with external services, such as those used for email marketing or cloud computing. For instance, a typical SPF record might contain entries like:

include:mailservice.com

include:cloudplatform.com

These mechanisms will individually conduct a DNS query to determine the IP addresses linked to those services.

2. Resolve IP Addresses

The subsequent step involves resolving the IP addresses linked to the specified domains. This is achieved through DNS lookups for each domain, which allows us to obtain their corresponding IP addresses. These addresses will then substitute the include mechanism within the SPF record.

As an illustration, should mailservice.com point to the IP addresses 192.168.1.1 and 192.168.1.2, the simplified SPF record would substitute the include:mailservice.com directive with these specific IP addresses:

ip4:192.168.1.1

Ip4:192.168.1.2

3. Combine the Results

After resolving all the IP addresses, they are merged into one SPF record. This minimizes dependence on external DNS queries and guarantees that the SPF record remains within the 10-lookup constraint.

A flattened SPF record could appear as follows:

v=spf1 ip4:192.168.1.1 ip4:192.168.1.2 ip4:203.0.113.4 -all

In this case, all permitted IP addresses are explicitly listed in the SPF record, which removes the necessity for additional DNS queries.

Benefits of SPF Flattening

Streamlining your SPF record can offer several important advantages:

1. Avoid Exceeding DNS Lookup Limits

The main advantage of simplifying an SPF record is that it helps avoid surpassing the DNS lookup threshold of 10. This guarantees that your emails successfully undergo SPF verification, preventing them from being rejected or classified as spam.

2. Improved Email Deliverability

A streamlined SPF record allows for quicker validation and reduces the risk of misconfigurations, thereby enhancing the chances that your emails will land in the inbox rather than being filtered into the spam folder.

Challenges and Considerations

Although SPF flattening provides distinct advantages, it also presents certain difficulties:

• Modifying IP Addresses: When SPF records are flattened, any alterations to the IP addresses of the services included necessitate manual modifications. This process can become tedious if the services frequently change their IPs.


• Intricacy: Flattening SPF records can be complicated, particularly for domains that utilize several third-party services. Keeping these records accurate and functional demands careful oversight and precision. To uncover more, simply click the link.