The Difference Between SPF -all vs ~all

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Learn SPF record syntax, the difference between -all and ~all, and how these mechanisms impact email authentication, DMARC, and deliverability.

by Yunes Tarada

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The Difference Between SPF -all vs ~all
Table Of Contents−

Understanding SPF -all vs ~all mechanisms is crucial for email authentication. Learn how these SPF record endings affect email delivery and which one to choose for your domain security.

Table Of Contents

Key Takeaways

  • ~all and -all both indicate SPF failure for unauthorized senders, but -all signals stricter enforcement intent.
  • Receiving servers may treat -all more aggressively than ~all, depending on policy and reputation signals.
  • Start with ~all during monitoring to reduce the risk of rejecting legitimate email while you confirm all sending sources.
  • Use -all only after SPF sources are complete and DMARC reports confirm there are no authentication gaps.
  • DMARC defines how authentication failures are handled (monitor, quarantine, or reject).
  • Proper SPF optimization helps avoid the 10 DNS lookup limit as your email infrastructure grows.

Understanding SPF -all vs ~all is an important part of email authentication, because these mechanisms signal how receiving mail servers should treat emails sent from unauthorized sources. Both mechanisms indicate an SPF failure, but they communicate different levels of enforcement intent and can influence how mail is filtered or rejected depending on recipient policy.

The all mechanism appears at the end of an SPF record and is preceded by a qualifier such as – (hardfail) or ~ (softfail). Choosing between them depends on how complete your SPF record is and whether you are actively monitoring authentication results using DMARC.

This article explains how SPF -all and ~all work, how mailbox providers interpret them today, and when to use each safely without putting legitimate email delivery at risk.

Quick answer: Use ~all while validating senders and monitoring with DMARC. Move to -all only when SPF is complete and DMARC reports show no legitimate failures.

SPF Record Syntax and Mechanisms Explained

Before diving into the differences between SPF -all and ~all, it’s essential to understand the complete SPF record syntax and all available mechanisms. 

An SPF record follows a specific format that tells receiving mail servers which IP addresses and domains are authorized to send emails on behalf of your domain.

The basic SPF record syntax is: v=spf1 [mechanisms] [modifiers] [all]

SPF All Mechanism Options

The “all” mechanism at the end of your SPF record determines what happens when an email doesn’t match any of the authorized senders. Here are all four options:

MechanismNameResultAction
#NAME?PassPASSAccept all emails (not recommended)
?allNeutralNEUTRALNo policy specified
~allSoftfailSOFTFAILMark as suspicious but deliver
-allHardfailFAILReject unauthorized emails

SPF Record Examples

Here are practical examples of SPF records using different mechanisms:

  • Basic SPF with Softfail: v=spf1 include:_spf.google.com ~all
  • Multiple includes with Hardfail: v=spf1 include:spf.protection.outlook.com include:_spf.salesforce.com -all
  • IP addresses with Softfail: v=spf1 ip4:192.168.1.0/24 ip6:2001:db8::/32 ~all
  • Mixed mechanisms: v=spf1 a mx include:_spf.google.com ip4:203.0.113.0/24 -all

SPF -all vs ~all

Both the SPF -all and SPF ~all mechanisms signify a “NOT PASS” for SPF authentication. In recent times, email providers use SPF results as one input among many, with DMARC policy and reputation signals heavily influencing final delivery decisions.

However, this was not the case a few years ago.

What does v=spf1 -all mean? 

The SPF record ending with “-all” (hardfail) instructs receiving mail servers to reject any emails that don’t come from authorized senders listed in your SPF record. This is the strictest SPF policy and provides the strongest protection against email spoofing.

What does ~all mean in SPF? 

The “~all” (softfail) mechanism tells receiving servers that emails from unauthorized senders should be marked as suspicious but still delivered to the recipient’s inbox, often to the spam folder.

How did the SPF all (Softfail vs Fail) Mechanism Operate Before DMARC?

DMARC was created a long time after SPF had already been in the market as the standard email authentication protocol. At this time the SPF -all softfail mechanism operated in the following way: 

Let’s suppose your SPF record was: 

v=spf1 include:spf.domain.com ~all (where ~all signifies SPF Softfail) 

Your receiver’s email server would have performed a DNS lookup to query the sender’s DNS for their SPF record. If the email’s Return-path domain was not listed in the sender’s record, the receiving server would have returned an SPF “NOT PASS” result but would have delivered the email to the inbox of the receiver. 

Now let’s suppose your SPF record was: 

v=spf1 include:spf.domain.com -all (where -all signifies SPF Fail) 

Your receiver’s email server would have performed a DNS lookup to query the sender’s DNS for their SPF record. If the email’s Return-path domain was not listed in the sender’s record, the receiving server would have returned an SPF “NOT PASS” result, but in this case, the email would have been rejected and not delivered to the inbox of the receiver.

Read more about the history of Sender Policy Framework. 

How to Simplify SPF Record Management

Managing SPF records can become complex as organizations grow and add more email sending services. The 10 DNS lookup limit is a common challenge that causes SPF authentication failures when exceeded. PowerDMARC’s automated SPF management solution addresses these challenges through advanced optimization techniques.

PowerDMARC’s SPF flattening technology automatically optimizes your SPF records to stay within DNS lookup limits while maintaining comprehensive email authentication coverage. This ensures your legitimate emails continue to authenticate properly even as you add new email services and marketing tools.

Simplify SPF with PowerDMARC!

Start 15-day trial Book a demo

How do Email Service Providers Handle the SPF -all vs ~all Mechanism Now?

Modern email service providers like Gmail, Outlook, and Yahoo handle SPF mechanisms differently than in the pre-DMARC era. Most major providers now focus on DMARC policies rather than individual SPF results when making delivery decisions.

  • Gmail’s approach: Gmail treats SPF softfail (~all) as a weaker authentication signal, while hardfail (-all) can increase suspicion for messages that do not match authorized sending sources. Final delivery decisions depend on DMARC policy and other filtering signals.
  • Microsoft Outlook handling: Outlook.com and Microsoft 365 consider SPF results as part of their filtering and authentication evaluation. A hardfail (-all) may be treated more strictly than a softfail (~all), but final handling still depends on DMARC policy and additional signals.

While you are free to use SPF -all or ~all for most mailbox providers at the current time without having to worry about delivery failures for legitimate emails, there can arise a situation where a server rejects your email in case of the -all attribute. Just to be on the safer side, you can avoid using the SPF hard fail -all mechanism while creating your SPF record. This is how you do it:

  • Open the PowerDMARC SPF record generator to start creating a record for free
  • After including the IP addresses and domains or your email senders scroll down to the last section designated to instruct email server’s how strict they should be while verifying your emails
  • Choose the “Soft-fail” option before hitting the “Generate SPF Record” button

What Do We Recommend? SPF -all or SPF ~all

Use SPF ~all (softfail) if:

  • You’re new to email authentication and want to minimize delivery risks
  • Your organization frequently adds new email sending services
  • You haven’t implemented DMARC monitoring yet
  • You’re in a testing phase and want to observe authentication results

Use SPF -all (hardfail) if:

  • You have DMARC properly configured and monitored
  • Your SPF record includes all legitimate sending sources
  • You want maximum protection against email spoofing
  • Your email infrastructure is stable and well-documented

The issues with email deliverability pertaining to the SPF -all mechanism might occur on very rare occasions. This is not a recurring problem that you will come across often. To ensure you never run into this problem, you can take the following steps:

  • Configure DMARC for your emails, and enable DMARC reporting
  • Set your DMARC policy to monitoring and closely inspect your SPF authentication results to spot any inconsistencies in email deliverability
  • If all is good, you can use the -all mechanism in your SPF record. We recommend using the hard fail attribute since it affirms that you are confident regarding the authenticity of your emails, which can boost your domain’s reputation

If you are currently unsure about using SPF -all, you can follow these steps:

How To Troubleshoot Common SPF Record Errors 

SPF errors usually fall into four buckets: record missing, record duplicated, record invalid, or DNS lookups failing. Use the error label below to pinpoint the fix quickly.

Common SPF errors include:

  • SPF PermError: Your SPF record is invalid. This typically happens due to syntax mistakes or because the record exceeds the 10 DNS lookup limit (for example, too many include mechanisms).
  • SPF TempError: A temporary DNS resolution problem (timeouts, transient DNS failures). This may resolve on its own, but repeated TempErrors usually indicate unstable DNS or name server issues.
  • SPF None: No SPF record was found for the domain being checked. This often means SPF isn’t published, is published on the wrong domain, or DNS hasn’t propagated.
  • Multiple SPF records: More than one SPF TXT record exists for the same domain, which breaks SPF evaluation and commonly results in authentication failures.

If you frequently see “No SPF record found”, it means the receiving server returned a null result when querying DNS for your SPF TXT record. This can be caused by a missing record, incorrect domain being checked (Return-Path vs From), or DNS publishing/propagation issues. (Link to your “No SPF record found” article here.)

If you have DMARC configured alongside SPF, receiving servers will also evaluate your DMARC policy to decide how to treat messages that fail authentication. Based on your policy, failed messages may be delivered, quarantined, or rejected. A DMARC reject policy can significantly reduce impersonation attacks like spoofing and phishing by telling receivers to block unauthenticated mail.

PowerDMARC’s SPF monitoring helps you spot these errors early by flagging authentication issues, surfacing the root cause, and guiding you through fixes before deliverability is impacted.

Frequently Asked Questions

What does v=spf1 -all mean?

The SPF record “v=spf1 -all” means that only the IP addresses and domains explicitly listed in the SPF record are authorized to send emails for your domain. Any emails from unauthorized sources will be rejected (hardfail). This is the strictest SPF policy and provides maximum protection against email spoofing.

What is the difference between SPF and DKIM?

SPF (Sender Policy Framework) validates that emails come from authorized IP addresses, while DKIM (DomainKeys Identified Mail) uses cryptographic signatures to verify email integrity and authenticity. SPF checks the sending server, while DKIM checks the email content hasn’t been tampered with during transit.

Is SPF all the same across different email providers?

No, different email providers may interpret SPF results differently. While most modern providers follow similar standards, some may be more lenient with softfail (~all) results while others strictly enforce hardfail (-all) policies. DMARC helps standardize these behaviors across providers.

What does +all do in SPF?

The “+all” mechanism in SPF means “pass all” – it allows any IP address to send emails on behalf of your domain. This is highly discouraged as it provides no protection against email spoofing and essentially makes your SPF record ineffective.

Should I use SPF -all or ~all for my domain?

Start with ~all (softfail) while you’re still confirming all legitimate sending sources or your setup is changing. Switch to -all (hardfail) only after your SPF record is complete and DMARC reporting shows legitimate emails aren’t failing authentication, so you can enforce stricter protection with lower risk.

How do I fix SPF authentication failures?

Common fixes include: adding missing IP addresses or domains to your SPF record, reducing DNS lookups to stay under the 10-lookup limit, removing duplicate SPF records, and ensuring proper SPF record syntax. PowerDMARC’s automated SPF management can help resolve these issues automatically.

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