--- title: "What are dangling SPF records and why are they a threat to email security? | AutoSPF" description: "SPF records are highly sensitive - even a minor change can invalidate them or trigger an error, resulting in improper email authentication." image: "https://autospf.com/og/blog/what-are-dangling-spf-records-and-email-security-threats.png" canonical: "https://autospf.com/blog/what-are-dangling-spf-records-and-email-security-threats/" --- Quick Answer SPF records are highly sensitive - even a minor change can invalidate them or trigger an error, resulting in improper email authentication. Dangling SPF records, which are basically records that include references to domains or subdomains that no longer exist or are misconfigured, also arise from this sensitivity. What are dangling SPF records and why are they a threat to email security? Your browser does not support the audio element. [ Download episode](/audio/what-are-dangling-spf-records-and-email-security-threats.mp3) Share [ ](https://www.linkedin.com/sharing/share-offsite/?url=https%3A%2F%2Fautospf.com%2Fblog%2Fwhat-are-dangling-spf-records-and-email-security-threats%2F "Share on LinkedIn") [ ](https://twitter.com/intent/tweet?text=What%20are%20dangling%20SPF%20records%20and%20why%20are%20they%20a%20threat%20to%20email%20security%3F&url=https%3A%2F%2Fautospf.com%2Fblog%2Fwhat-are-dangling-spf-records-and-email-security-threats%2F "Share on X/Twitter") [ ](https://www.facebook.com/sharer/sharer.php?u=https%3A%2F%2Fautospf.com%2Fblog%2Fwhat-are-dangling-spf-records-and-email-security-threats%2F "Share on Facebook") [ ](https://reddit.com/submit?url=https%3A%2F%2Fautospf.com%2Fblog%2Fwhat-are-dangling-spf-records-and-email-security-threats%2F&title=What%20are%20dangling%20SPF%20records%20and%20why%20are%20they%20a%20threat%20to%20email%20security%3F "Share on Reddit") [ ](mailto:?subject=What%20are%20dangling%20SPF%20records%20and%20why%20are%20they%20a%20threat%20to%20email%20security%3F&body=Check out this article: https%3A%2F%2Fautospf.com%2Fblog%2Fwhat-are-dangling-spf-records-and-email-security-threats%2F "Share via Email") ![SPF records](https://media.mailhop.org/autospf/images/2025/04/spf-flattening-1189.jpg) SPF records are highly sensitive - even a minor change can invalidate them or trigger an error, resulting in improper email authentication. Dangling [SPF records](/explaining-sender-policy-framework-spf-macros/spf-record-syntax/), which are basically records that include references to domains or subdomains that no longer exist or are misconfigured, also arise from this sensitivity. _Per [RFC 7208](https://datatracker.ietf.org/doc/html/rfc7208), SPF evaluation is capped at 10 DNS mechanism lookups and 2 void lookups per check - exceeding either limit produces a `PermError` that fails authentication for every message from the domain._ Sometimes you disassociate with a third-party vendor, but forget to remove their sending sources from your SPF record, which also results in a dangling SPF record. These small remnants appear innocent and harmless from a non-technical person’s point of view, but an [email authentication](/blog/role-relevance-of-dns-spf-records-for-email-authentication/) expert knows how these mistakes undermine the entire purpose of deploying SPF in the first place. In short, a dangling SPF record points to something that is insecure or broken. Let’s see how this is a threat to your company’s [email security](/blog/why-spf-prevailed-among-other-email-security-solutions/). ![cyber actors](https://media.mailhop.org/autospf/images/2025/04/spf-validator-7111.jpg) ## How do cyber actors exploit dangling SPF records? [Threat actors](https://cybersecuritynews.com/threat-actors-targeting-local-communities-in-the-u-s/) are always on the lookout for misconfigurations in systems that they can exploit for their malicious purposes. A dangling SPF record is one such exploitable vulnerability that poses the following threats- ### 1\. Abuse by attackers (Subdomain takeover) It’s dangerous if your SPF record includes a domain that has expired or is no longer under your control. Attackers can register the abandoned domain, set up a [mail server](https://www.cloudflare.com/learning/email-security/what-is-a-mail-server/) under it, and send [malicious emails](https://www.securitymagazine.com/articles/100687-the-last-six-months-shows-a-341-increase-in-malicious-emails) from it. Since your SPF record includes the now-compromised domain, the emails sent from it will pass SPF authentication checks without an issue. ### 2\. Bypassing security filters Dangling SPF records are the ideal backdoors for malicious actors. What they do is insert their own [IP addresses](https://www.techtarget.com/whatis/definition/IP-address-Internet-Protocol-Address#:~:text=An%20Internet%20Protocol%20%28IP%29%20address,for%20communicating%20across%20the%20internet.) in a poorly maintained or misconfigured [third-party domain](https://www.lawinsider.com/dictionary/third-party-domain) that is included in your SPF record. This way, they can send [spoofed and phishing](https://thehackernews.com/2024/07/proofpoint-email-routing-flaw-exploited.html) emails that appear SPF-aligned and bypass security filters. Since SPF is one of the key mechanisms used by [spam filters](https://www.fortinet.com/resources/cyberglossary/spam-filters) and security gateways, a successful bypass means malicious emails, including spam, malware, or phishing content, can land directly in the recipient’s inbox, often without raising any suspicion. ![email deliverability ](https://media.mailhop.org/autospf/images/2025/04/spf-record-syntax-6722.jpg) ### 3\. Hampered email deliverability It’s not only the illegitimate email flow that’s affected by dangling SPF records; a less obvious impact of dangling SPF records also affects the [legitimate email](https://www.usatoday.com/story/tech/2021/08/23/gmail-spam-filter-email-inbox-google/8242847002/) flow. If your SPF record points to a non-existent or unreachable domain, it exceeds the DNS lookup limit of 10\. If that happens, the receiving mailboxes reject your emails outright or place them in spam folders. This can harm your domain’s [email reputation](https://www.campaignmonitor.com/resources/knowledge-base/what-is-email-sender-reputation/), impacting everything from [transactional emails](https://developer.dotdigital.com/docs/transactional-email) to critical client communications. Worse still, you may not be immediately aware of these issues unless you actively monitor your SPF configuration and email logs. ![transactional emails](https://media.mailhop.org/autospf/images/2025/04/spf-flattening-7793.jpg) ### 4\. Silent failures The issues arising from dangling records are not always immediately apparent on the surface. _For example, if there is an expired domain in your SPF record, it might not trigger any delivery problems; however, it might lead to intermittent or partial failures, depending on how each server handles the issue_. ## Final words Dangling [SPF](/blog/what-is-spf-email-a-guide-to-sender-validation-technology/) records defy the intentions of protecting emails through authentication protocols. You must leverage [DMARC](https://dmarcreport.com/) reporting tools so that issues like reduced deliverability and reaching the lookup limit don’t go undetected for months. However, if your SPF record has already exceeded the [SPF DNS lookup limit](/blog/spf-dns-lookup-limits-exploits-mitigations-and-best-practices/) of 10, then use our [automatic flattening tool](/) to fix the issue. ## Topics [ DKIM ](/tags/dkim/)[ DMARC ](/tags/dmarc/)[ email security ](/tags/email-security/)[ SPF ](/tags/spf/)[ SPF record ](/tags/spf-record/) ![Brad Slavin](https://media.mailhop.org/autospf/images/authors/brad-slavin.jpg) [ Brad Slavin ](/authors/brad-slavin/) General Manager Founder and General Manager of DuoCircle. Product strategy and commercial lead for AutoSPF's 2,000+ customer base. [LinkedIn Profile →](https://www.linkedin.com/in/bradslavin) ## Ready to get started? Try AutoSPF free — no credit card required. [ Book a Demo ](/book-a-demo/) ## Related Articles [ Intermediate 3m 3 points to consider before setting your SPF record to -all (HardFail) May 22, 2025 ](/blog/3-points-to-consider-before-setting-your-spf-record-hardfail/)[ Intermediate 5m Are Your SPF and DKIM Identifiers Aligned? Jul 18, 2024 ](/blog/are-your-spf-and-dkim-identifiers-aligned/)[ Intermediate 6m Automated Solutions for Preventing Email Spoofing May 7, 2026 ](/blog/automated-solutions-for-preventing-email-spoofing/)[ Intermediate 7m AutoSPF Explains: The Definitive Guide to Adding an SPF Record to Cloudflare Jan 7, 2026 ](/blog/autospf-definitive-guide-adding-spf-record-cloudflare/) ```json {"@context":"https://schema.org","@type":"Organization","@id":"https://www.wikidata.org/wiki/Q138897474","name":"AutoSPF","url":"https://autospf.com","logo":{"@type":"ImageObject","url":"https://autospf.com/images/autospf-logo.png"},"description":"Automatic SPF flattening and email authentication management. 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