--- title: "SPF record +all mechanism- why is it the most dangerous SPF setting | AutoSPF" description: "SPF prevents emails sent by unauthorized people from landing in the inboxes of targeted recipients." image: "https://autospf.com/og/blog/spf-record-all-mechanism-why-most-dangerous-spf-setting.png" canonical: "https://autospf.com/blog/spf-record-all-mechanism-why-most-dangerous-spf-setting/" --- Quick Answer SPF prevents emails sent by unauthorized people from landing in the inboxes of targeted recipients. However, if your SPF record is misconfigured, it can do more harm than good- especially if it’s overly permissive. By overly permissive, we mean using the +all mechanism, as this setting can turn your domain into an open relay for cybercriminals. Share [ ](https://www.linkedin.com/sharing/share-offsite/?url=https%3A%2F%2Fautospf.com%2Fblog%2Fspf-record-all-mechanism-why-most-dangerous-spf-setting%2F "Share on LinkedIn") [ ](https://twitter.com/intent/tweet?text=SPF%20record%20%2Ball%20mechanism-%20why%20is%20it%20the%20most%20dangerous%20SPF%20setting&url=https%3A%2F%2Fautospf.com%2Fblog%2Fspf-record-all-mechanism-why-most-dangerous-spf-setting%2F "Share on X/Twitter") [ ](https://www.facebook.com/sharer/sharer.php?u=https%3A%2F%2Fautospf.com%2Fblog%2Fspf-record-all-mechanism-why-most-dangerous-spf-setting%2F "Share on Facebook") [ ](https://reddit.com/submit?url=https%3A%2F%2Fautospf.com%2Fblog%2Fspf-record-all-mechanism-why-most-dangerous-spf-setting%2F&title=SPF%20record%20%2Ball%20mechanism-%20why%20is%20it%20the%20most%20dangerous%20SPF%20setting "Share on Reddit") [ ](mailto:?subject=SPF%20record%20%2Ball%20mechanism-%20why%20is%20it%20the%20most%20dangerous%20SPF%20setting&body=Check out this article: https%3A%2F%2Fautospf.com%2Fblog%2Fspf-record-all-mechanism-why-most-dangerous-spf-setting%2F "Share via Email") ![SPF record +all mechanism](https://media.mailhop.org/autospf/images/2025/02/spf-record-example-7456.jpg) [SPF](/blog/what-is-spf-email-a-guide-to-sender-validation-technology/) prevents emails sent by unauthorized people from landing in the inboxes of targeted recipients. However, if your SPF record is misconfigured, it can do more harm than good- especially if it’s overly permissive. By overly permissive, we mean using the +all mechanism, as this setting can turn your domain into an open relay for cybercriminals. _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._ For a deep dive into every SPF mechanism, qualifier, and modifier, see our [complete SPF record syntax guide](/blog/spf-record-syntax-complete-guide/). We say this because the +all mechanism allows any server on the internet to send emails using your domain. SPF’s purpose is to allow only authorized servers to be used to send emails, but the +all mechanism defies that. It negates SPF protection, making SPF completely ineffective in preventing [spoofing and phishing](https://thehackernews.com/2024/07/proofpoint-email-routing-flaw-exploited.html). _In this blog, we’ll explore why +all is a security risk, how attackers exploit it, and what you should do instead to ensure a secure SPF configuration_. ## How do threat actors exploit the +all mechanism vulnerability? The +all mechanism is one of the most dangerous misconfigurations because, with this, you officially authorize every email server to be used for sending emails on behalf of your company and using your domain. This is a goldmine situation for [cybercriminals](https://www.voanews.com/a/cybercriminals-increasingly-help-russia-china-iran-target-us-allies-/7822907.html) because- ### 1\. It makes it easier to send spoofing and phishing emails It enables attackers to forge emails from your domain and send [phishing emails](https://www.techtarget.com/searchsecurity/news/366547912/Researchers-put-LLMs-to-the-test-in-phishing-email-experiment) to your customers, partners, employees, etc. _Since the emails land in their inboxes without any warning, recipients treat them as normal_. They trust the emails to be genuinely coming from you and hence end up sharing [sensitive details](https://www.theguardian.com/us-news/2023/oct/06/donald-trump-us-nuclear-submarines-potentially-sensitive-information-australian-billionaire-anthony-pratt) (like bank information, medical reports, contact details, etc.), transferring money, [downloading malware-infected files](https://www.bleepingcomputer.com/news/security/the-most-common-malicious-email-attachments-infecting-windows/), etc. _Remind you that all this happens while believing that email has come from your company. So, if they become victims of any fraud, they will press charges against your company as you failed to protect them_. ### 2\. Your domain becomes a spam gateway Spammers treat your domain as a free channel to distribute bulk [spam emails](https://cybernews.com/news/microsofts-breach-notification-emails-end-up-in-spam-folder/). With so many emails sent from your domain, its [domain reputation](https://www.activecampaign.com/blog/domain-reputation) will be affected drastically. This way, email services like Gmail and Outlook will stop trusting your domain and start marking all emails from your domain as spam or malicious. ![spam emails](https://media.mailhop.org/autospf/images/2025/02/spf-permerror-9768.jpg) ### 3\. Bypassing DMARC protections becomes an easy deal _An overly permissive SPF record can weaken DMARC protection_. Even if you have DMARC set up, a fake email could pass both SPF and [DMARC](/10-reasons-for-regular-spf-record-checks-in-cybersecurity/dmarc-record-check/) if SPF is misconfigured (ignoring [DKIM](/10-reasons-for-regular-spf-record-checks-in-cybersecurity/dkim-record-check/) for now). If an email fails DMARC checks, one of the following actions is taken against it- - _If you have set your DMARC record to p=none policy, no action will be taken against it. It will land in the recipient’s inbox, as usual_. - If you have set your DMARC record to p=quarantine, it will be sent to the recipient’s spam folder. - If you have set your DMARC record to p=reject, it will bounce back to the sender. ### 4\. Puts your business at risk _If cybercriminals use your domain for phishing, customers may lose trust in your brand_. In industries like finance or healthcare, allowing your domain to be exploited for [email fraud](https://komonews.com/news/local/five-sisters-multi-state-mail-fraud-scheme-retail-fraudulent-returns-assistant-united-states-attorney-rachel-yemini-homeland-security-investigations-post-office-250000-fine-indictment) can result in legal consequences. ## How Do You Fix it the right way? Firstly, you need to know if the +all misconfiguration exists in your [SPF record](/spf-record-checker/create-spf-record/). We recommend that you frequently run your SPF record through a credible online lookup tool. It runs a quick scan and shows all the problems and misconfigurations. If you detect this misconfiguration, correct it immediately by replacing it with either -all or \~all. - \-all (Hard Fail) is the safest option as it rejects [unauthorized emails](https://news.trendmicro.com/2023/12/05/unauthorized-log-in-attempt-notification-email/) outright. - \~all (Soft Fail) marks unauthorized emails as suspicious, but they still get delivered. In simple words, these are placed in the [spam folder](https://cybernews.com/news/microsofts-breach-notification-emails-end-up-in-spam-folder/). ![email security](https://media.mailhop.org/autospf/images/2025/02/spf-record-tester-64123.jpg) Also, as a crucial step in maintaining [email security](/), ensure that you enlist only the [email servers](https://www.one.com/en/email/what-is-an-email-server) you trust to send emails on your behalf using your domain. ## Topics [ 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 [ Advanced 10m AutoSPF’s Guide to Configuring SPF & DKIM for Avanan: A Detailed Walk-through Nov 26, 2025 ](/blog/autospf-guide-configuring-spf-dkim-for-avanan-detailed-setup-walkthrough/)[ Advanced 24m Best DNS Security Tools for Email in 2026 SPF, DKIM & DMARC Management Compared Apr 28, 2026 ](/blog/best-dns-security-tools-email-2026-spf-dkim-dmarc-compared/)[ Advanced 23m Best Email Authentication Tools For Enterprise in 2026 The Complete Guide Apr 30, 2026 ](/blog/best-email-authentication-tools-enterprise-2026-complete-guide-solutions/)[ Advanced 30m Best SPF Management Tools for MSPs in 2026 A Buyer’s Guide Apr 27, 2026 ](/blog/best-spf-management-tools-for-msps-in-2026-buyers-guide/) ```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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