These days, every website is on the radar of malicious actors; doesn’t matter if you own a multi-national company or a home-grown e-commerce platform. You have a website, that means you have to be cautious and driven towards email authentication based on SPF, DKIM, and DMARC.

An SPF record is a TXT-type record that includes all the IP addresses and mail servers that domain owners officially allow to be used for sending and receiving email messages on behalf of their organizations. SPF records are published on DNS, and recipients’ mail servers have to perform DNS lookups to retrieve them to conduct the validation process. 

However, as per RFC7208, there’s a maximum limit of 10 DNS lookups per SPF record. Once the limit is reached, the SPF DNS record becomes erroneous. SPF record flattening helps take care of this problem for you. So, dig into this detailed blog on the same. We’ll touch base on everything important.


Reasons for the SPF DNS Lookup Limit

Before we talk about why every website needs an SPF record flattener, let’s quickly know why this limit is imposed in the first place-



The more the number of DNS lookups, the slower the processing and transmitting process, especially for busy email servers. The limit prevents the overburdening of the resources and prompts responsiveness.


Abuse Prevention

Without this limit, hackers can flood recipients’ mail servers with DNS queries, triggering Distributed Denial-of-Services or DDoS attacks.



Handling an arbitrary number of DNS lookups for SPF checks could lead to overly complex email server configurations and make it difficult to predict the processing time for incoming emails. 


How SPF works


How SPF works

Image sourced from


What is Flattening an SPF Record?

SPF record flattening simplifies and optimizes SPF records by reducing the number of DNS lookups required for the authentication process. This also minimizes the likelihood of getting legitimate emails marked as spam, which is also called instances of false positives


How Does SPF Record Flattening Work?

SPF flattening works by saving you from the ‘Permerror SPF permanent error too many DNS lookups’, which could otherwise wreak havoc on your authentication process.

An SPF flattener is a tool that automatically condenses the submitted record by removing mechanisms like ‘a,’ ‘mx,’ and ‘include’ to eliminate the need for additional lookups. Also, the domains earlier pointed to by the SPF mechanisms are represented solely by a string of ip4 and ip6 rules in a single SPF record. 



Let’s say you submitted an SPF record with an ‘include’ mechanism for your outsourced marketing agency, which included several domains. Now, an automatic SPF flattener would resolve all these includes and macros into a single, flat SPF record with a list of IP addresses and mechanisms.


5 Compelling Reasons to Use SPF Record Flattening Services

As per an IBM report, phishing is the second most common cause of data breaches. Implementation of SPF prevents that from happening only if the record is devoid of any errors, including ‘SPF Permerror’. So, here we have enlisted 5 reasons why you should not overlook an SPF flattener.


1. Avoiding DNS Lookup Limits

Each DNS lookup consumes server resources, which causes delays in email transmission and delivery. SPF flattening minimizes the requirement for SPF DNS lookups, which resolves the issue of overburdening the resources to go through a smoother email transmission


2. Mitigating the SPF Record Size Limitation

An SPF record can’t exceed the limit of 255 characters, and complex or overly fragmented records often violate this. This triggers email authentication failures and gives phishers the opportunity to exploit reputed domains to their advantages. SPF flattening services make them concise and compliant with this limitation.


3. Boosting Email Deliverability

Some email servers find it challenging and resource-exhausting to interpret complex or nested SPF TXT records. SPF flattening streamlines the SPF record, making it easier for receiving servers to process and reduce the risk of legitimate emails being marked as spam or rejected due to SPF record complexity.



4. Reducing Risks of Misconfigurations

Handling several SPF records leads to misconfigurations, including conflicting rules or omitted senders. An SPF flattening tool reduces the instances of errors by compressing all authorized sources into a single, comprehensive, inclusive, yet simplified record that takes care of misconfigurations.


5. Maintaining Consistency

The existence of multiple SPF records makes it challenging to maintain uniformity across all of them. Varying instructions and the utility of mechanisms cause troubles at receivers’ ends, prompting validation issues like false positives. 

SPF record flattening eliminates the need to make updates to multiple records, which consequently leaves no room for varied instructions for recipients’ mailboxes. 


How to Know if Your SPF Record Has Exceeded the SPF Lookup Limit?

There are a few ways to figure out how far before your SPF record hits the SPF lookup limit and becomes invalid.


Review Your SPF Record

Look for the ‘include’ and ‘a’ mechanisms as they require DNS lookups. Note all these mechanisms.


Count DNS Lookup Mechanisms

Count how many DNS lookup mechanisms are there in your SPF record. Each instance of ‘include’ or ‘a’ mechanism count towards one lookup. So, if there are 2 ‘include’ mechanisms and 1 ‘a’ mechanism, then it counts to 3 DNS lookups


Check Third-Party Services

If your SPF record has included sending sources of third-party vendors, then they would also count towards the lookup limit.

For example, if you’re including a service like Google Workspace (G Suite), it will consume a DNS lookup.


Consider Other Mechanisms

Mechanisms like ‘mx’ and ‘ip4’ aren’t counted towards the limit, but they contribute to make your SPF record lengthy, potentially triggering issues.



Use an SPF Lookup Tool

An SPF lookup tool highlights all the existing errors in the queried domain’s record. It cross-checks your record against a number of elements, including the DNS lookup count.


Consult a Specialist

DuoCircle is the platform that resolves all your email authentication issues and fixing the Permerror is no big deal for us. We use automatic tools to condense your SPF record to get rid of redundant and unnecessary mechanisms and IP addresses, eliminating or reducing the need for DNS lookups.

We offer digital solutions against email-based phishing attacks and ensure every IT-driven business owner lives with a head-high reputation. Get in touch with us for SPF, DKIM, and DMARC implementation and monitoring.

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