---
title: "Understanding the use cases for SPF soft fail and hard fail | AutoSPF"
description: "SPF works on two core components: soft fail and hard fail. Domain owners should understand the conditions under which each of these mechanisms works perfectly."
image: "https://autospf.com/og/blog/spf-soft-fail-and-hard-fail-use-cases-explained.png"
canonical: "https://autospf.com/blog/spf-soft-fail-and-hard-fail-use-cases-explained/"
---

Quick Answer

SPF works on two core components: soft fail and hard fail. Domain owners should understand the conditions under which each of these mechanisms works perfectly. A mindless implementation of mechanisms leads to poor email deliverability and sender reputation, impacting communication and brand integrity. While the soft fail mechanism is lenient, it leaves a security gap.

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![SPF soft fail and hard fail](https://media.mailhop.org/autospf/images/2024/11/kitterman-spf-1.jpg) 

SPF works on two core components: [soft fail and hard fail](/blog/spf-soft-fail-and-hard-fail-in-email-marketing/). Domain owners should understand the conditions under which each of these mechanisms works perfectly. A mindless implementation of mechanisms leads to poor [email deliverability](/blog/how-does-spf-help-marketers-in-improving-email-deliverability/) and [sender reputation](https://www.forbes.com/councils/forbescommunicationscouncil/2019/07/23/improve-your-email-sender-reputation-in-three-steps/), impacting communication and [brand integrity](https://www.channelsight.com/blog/brand-integrity). While the soft fail mechanism is lenient, it leaves a security gap. However, hard fail is too strict and can cause some of your legitimate emails to land in the [spam folders](https://cybernews.com/news/microsofts-breach-notification-emails-end-up-in-spam-folder/). 

This blog clearly mentions when to use which of the two [SPF mechanisms](/blog/decoding-spf-mechanisms-and-their-role-in-maximizing-email-deliverability/). 

## 1\. SPF soft fail (\~all)

A soft fail mechanism tells receiving [mail servers](https://www.cloudflare.com/learning/email-security/what-is-a-mail-server/) to accept emails failing the SPF check but mark them as suspicious. This reduces the chances of targeted recipients interacting with [fraudulent emails](https://www.khon2.com/news/watch-out-for-fake-package-tracking-emails/) and getting duped. 

Here are the technical use cases of SPF soft fail-

### How Do You Verify and gradual deployment of SPF records?

When initially deploying [SPF](/blog/what-is-spf-email-a-guide-to-sender-validation-technology/), using \~all allows you to observe how the SPF record affects email delivery without outright rejecting [unauthorized emails](https://news.trendmicro.com/2023/12/05/unauthorized-log-in-attempt-notification-email/). _For example, you can monitor email logs to spot legitimate senders that you have to add to your SPF record_.

### Organizations with complex and decentralized email infrastructure

Companies with multiple [third-party vendors](https://www.upguard.com/blog/third-party-vendor) or poorly documented email systems may use \~all to prevent inadvertently rejecting legitimate emails. This is because if your email setup is complex, there will be multiple IPs and subdomains involved. Using a soft fail avoids disruption in communication by ensuring emails that didn’t pass the SPF check are tagged as spam and blocked outrightly. 

![malicious email](https://media.mailhop.org/autospf/images/2024/11/spf-record-example-4785.jpg) 

### To prevent overly aggressive email rejection

If you are unsure about the completeness of your [SPF record](/spf-record-checker/create-spf-record/), you should stick to soft fail to avoid aggressive rejections and allow gradual fine-tuning. _This situation arises if your company or domain is new, you’ve recently hired many employees, or you’ve acquired multiple new devices_.

### For supporting compatibility with forwarding

When emails are forwarded, they often fail SPF checks because the sender’s IP (forwarding server) doesn’t match the SPF record. The SPF check compares the originating IP address with the domain’s SPF record. _Forwarding servers are typically not listed in the original sender’s SPF record, causing the email to fail the check_.

So, if you stick to the soft fail mechanism in such scenarios, then [legitimate emails](https://www.usatoday.com/story/tech/2021/08/23/gmail-spam-filter-email-inbox-google/8242847002/) from your domain won’t take a toll. We encourage pairing up SPF with [DMARC](/10-reasons-for-regular-spf-record-checks-in-cybersecurity/dmarc-record-check/) for such conditions because when you deploy DMARC policy with a ‘relaxed’ alignment mode, delivery issues are minimized. 

## 2\. SPF hard fail (-all)

The hard fail mechanism tells receiving mail servers to reject emails that fail the [SPF check](/spf-record-checker/) outright.

Here are the technical use cases of SPF hard fail-

### Strict email authentication for high-security domains

Domains that need to maintain a high level of trust (e.g., banks, government entities) often use -all to block [spoofed emails](https://www.pcmag.com/news/nsa-warns-of-north-korean-hackers-spoofing-emails-from-legit-domains) completely. These institutions have to ensure that only authorized servers can send emails.

![Phishing and spoofing mitigation](https://media.mailhop.org/autospf/images/2024/11/spf-lookup-3.jpg) 

### Phishing and spoofing mitigation

Domains can reduce the risk of their brand being exploited in [phishing attacks](https://www.bleepingcomputer.com/news/security/office-365-phishing-attack-impersonates-the-us-department-of-labor/) by enforcing a hard fail. _Since the unauthorized email is rejected, attackers are less likely to succeed in impersonating the domain_.

### Clear and controlled email infrastructure

Organizations with well-documented and controlled [email systems](https://cybersecuritynews.com/russian-spies-hacked-microsoft/) can confidently implement -all. For example, a small business with a single mail server can use -all without risking disruptions.

## Final thoughts

In conclusion, understanding the nuances between SPF soft fail (\`\~all\`) and hard fail (\`-all\`) is essential for crafting an effective [email authentication](/spf-too-many-dns-lookups/spf-lookup/) strategy. Each mechanism serves distinct purposes - soft fail is ideal for testing, gradual deployment, and accommodating complex or evolving [email infrastructures](https://www.voilanorbert.com/blog/email-infrastructure/), while hard fail is suited for domains with well-established systems and a critical need for stringent [email security](/?%5Fgl=1%2A1op2v35%2A%5Fup%2AMQ..%2A%5Fga%2ANDYxMTAwMzgxLjE3MjMwMzcwMDI.%2A%5Fga%5F5J0R8M01Y5%2AMTcyMzAzNzAwMS4xLjAuMTcyMzAzNzAwMS4wLjAuMA..).

When combined with complementary protocols like DMARC and [DKIM](/10-reasons-for-regular-spf-record-checks-in-cybersecurity/dkim-record-check/), SPF becomes a powerful tool to prevent email spoofing and protect your [brand’s reputation](https://www.prnewswire.com/news-releases/brand-reputation-at-risk-from-consumers-data-distrust-300955595.html). By carefully implementing and monitoring SPF policies, organizations can strike the right balance between security and email deliverability, ensuring both protection and communication efficiency.

## Topics

[ DKIM ](/tags/dkim/)[ email security ](/tags/email-security/)[ 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 6m  10 Reasons Why DIY-ing SPF isn’t a Good Choice for Companies  Apr 4, 2024 ](/blog/10-reasons-diy-ing-spf-isnt-good-choice-for-companies/)[  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/)

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