An SPF fail occurs when the receiving mail server can’t find the sending IP address in your domain’s SPF record. The server checks whether the IP that transmitted the email is authorized to send on your domain’s behalf — and when it isn’t listed, SPF fails.
The consequences range from spam folder placement to outright rejection, depending on how your record is configured and whether DMARC is in play.
For enterprise marketing teams sending through multiple platforms (Salesforce Marketing Cloud, Marketo, third-party vendors), SPF failures often stem from forgotten sending sources that were never added to DNS.
What SPF failure signals to receiving servers:
- The sending IP isn’t authorized for this domain
- The message might be spoofed or fraudulent
- Delivery should be blocked, flagged, or scrutinized
SPF failure isn’t always catastrophic. The specific type of failure — and your broader authentication setup — determines whether emails bounce, land in spam, or slip through anyway. Understanding the failure types helps you diagnose problems and implement targeted fixes.
What are the different types of SPF failure?
SPF doesn’t produce a simple pass/fail binary. The authentication check returns one of several results, each with different implications for deliverability.
Hard fail (-all)
The sending IP is explicitly not authorized. Your SPF record ends with -all, which instructs receivers to reject or discard unauthorized messages. Most servers will bounce the email entirely, returning a 550 error code.
Soft fail (~all)
The sending IP probably isn’t authorized, but the domain owner isn’t certain. Your record ends with ~all, suggesting receivers should accept the message but mark it as suspicious. Emails typically land in spam rather than being rejected.
Neutral (?all)
The domain makes no assertion about the IP’s authorization. Receivers treat this as “no opinion” — they won’t reject based on SPF alone, but won’t give the message any positive signal either.
None
No SPF record exists for the domain, or the record doesn’t produce a result. The domain is vulnerable to spoofing because there’s no sender policy to enforce.
| Result | Record ending | Receiver action |
| Hard fail | -all | Reject or bounce |
| Soft fail | ~all | Spam folder or flag |
| Neutral | ?all | No SPF-based action |
| None | No record | No verification possible |
For a deeper comparison of when to use each qualifier, see our guide on softfail vs hardfail.
What causes SPF to fail?
SPF failures stem from three categories: missing authorizations, technical errors, and mail flow complications. Identifying which category applies to your situation determines the fix.
Missing sending sources
The most common cause. Your SPF record doesn’t include all the servers that send email for your domain.
- Your ESP changed IP addresses without notifying you
- Acquired companies or subsidiaries use different sending systems
- New sending infrastructure was deployed, but DNS wasn’t updated
- Third-party vendors (marketing platforms, CRM systems, HR tools) weren’t added
Enterprise organizations running Marketo, Pardot, or Salesforce Marketing Cloud alongside transactional email systems often discover gaps when auditing their sending sources.
Syntax and configuration errors
SPF records follow strict formatting rules. Minor mistakes break the entire record.
- Missing v=spf1 tag at the beginning
- Typos, extra spaces, or hidden characters
- Using a deprecated SPF record type instead of TXT
- Multiple SPF records for one domain (only one is allowed)
- Incorrect mechanism syntax (wrong colons, missing IP prefixes)
DNS lookup limits
SPF enforces a 10-DNS-lookup limit to prevent abuse. Each include: mechanism and certain other mechanisms (a, mx, ptr, exists) count toward this limit.
- Too many third-party includes push you over the limit
- Nested includes (services that include other services) compound quickly
- Exceeding the limit returns a “permerror” — a permanent error that invalidates the entire record
SPF flattening replaces include mechanisms with IP addresses to reduce lookup count.
Mail forwarding
SPF rarely survives automatic forwarding. When someone forwards your email, the forwarding server’s IP transmits the message — but that IP isn’t in your SPF record.
The original sender’s SPF fails because the forwarding server isn’t authorized. This is a fundamental limitation of SPF, which is why DKIM (which survives forwarding) and DMARC (which can pass on DKIM alone) matter for complete authentication.
How do permerror and temperror differ from standard failures?
Beyond the qualifier-based results (fail, softfail, neutral), SPF can return error conditions that indicate processing problems rather than authorization decisions.
Permerror
A permanent error means the SPF record itself is broken and can’t be evaluated. Common causes:
- Syntax errors that prevent parsing
- The record exceeds 10 DNS lookups
- More than one SPF record exists for the domain
- More than 2 “void” lookups (queries returning no results)
- Record exceeds 255 characters per string or 512 bytes total
Permerror is worse than a standard fail because it signals misconfiguration rather than unauthorized sending. Fix the record structure before worrying about authorization.
Temperror
A temporary error caused by transient DNS issues — timeouts, server outages, or network problems. Temperrors often resolve on retry.
- Query timed out before completion
- DNS server temporarily unreachable
- Receiving server’s DNS resolution failed
| Error type | Cause | Action needed |
| Permerror | Broken SPF record | Fix the record immediately |
| Temperror | DNS/network issue | Usually resolves automatically |
Temperrors don’t require record changes, but persistent temperrors suggest DNS infrastructure problems worth investigating.
What happens to emails when SPF fails?
The consequences depend on your SPF qualifier, the receiver’s policies, and whether DMARC is configured.
Without DMARC
Receivers interpret your SPF result according to their own policies (which vary widely):
- Hard fail: Most servers reject or bounce the message
- Soft fail: Most servers deliver to spam or add warning headers
- Some servers ignore SPF entirely and rely on other reputation signals
The inconsistency is a problem — you can’t predict how different providers will handle failures.
With DMARC
DMARC standardizes the response. Your DMARC policy (none, quarantine, reject) tells receivers exactly what to do with failed messages.
However, it is important to note that DMARC treats hard fail and soft fail identically. Both count as “SPF failed” for DMARC evaluation. If your DMARC policy is p=reject and both SPF and DKIM fail, the message gets rejected regardless of whether your SPF record uses -all or ~all.
DMARC also requires alignment — the domain in the Return-Path (what SPF checks) must match the domain in the visible From header. An email can pass SPF technically, but still fail DMARC if alignment fails.
Deliverability impact
Repeated SPF failures damage sender reputation over time:
- Domain reputation scores decline
- Severe or persistent failures can trigger blacklisting
- ISPs associate your domain with authentication problems
- Future emails face increased scrutiny even when SPF passes
How do you diagnose SPF failures?
Pinpointing why SPF failed requires checking the failure type, reviewing your record configuration, and tracing the sending source.
Check email headers
Failed emails contain authentication results in headers. Look for lines like:
Authentication-Results: spf=fail (sender IP is X.X.X.X)
Received-SPF: fail (domain of example.com does not designate X.X.X.X as permitted sender)
The header reveals:
- Which IP address attempted to send
- What result SPF returned
- Why the check failed
Validate your SPF record
Use SPF lookup tools to verify your record is valid:
- Confirm only one SPF record exists
- Count DNS lookups (must be 10 or fewer)
- Check that v=spf1 appears at the beginning
- Test that the record doesn’t exceed size limits
- Verify all mechanisms are syntactically correct
Match IPs to your record
Compare the IP address from the failure header against your SPF record:
- Is the IP covered by an include: for your ESP?
- Is the IP included directly (via ip4: or ip6: mechanisms)?
- Did the sending service change IPs without notification?
Review DMARC reports
If you have DMARC configured with reporting (rua tag), aggregate reports show which IPs are sending for your domain and their authentication results. Reports reveal unauthorized senders and legitimate sources that aren’t in your SPF record.
How do you fix SPF failures?
The fix depends on the failure cause. Most issues fall into authorization gaps, record errors, or structural limits.
Add missing sending sources
Audit all services that send email for your domain and add them to your SPF record:
| Sending source | Typical include mechanism |
| Google Workspace | include:_spf.google.com |
| Microsoft 365 | include:spf.protection.outlook.com |
| Salesforce | include:_spf.salesforce.com |
| Marketo | include:mktomail.com |
| SendGrid | include:sendgrid.net |
| Mailchimp | include:servers.mcsv.net |
Your ESP’s documentation specifies the exact mechanism to add.
Fix syntax errors
Common corrections:
- Add v=spf1 at the beginning if missing
- Remove extra spaces and hidden characters
- Remove duplicate SPF records (keep only one)
- Verify mechanism syntax matches the specification
- Publish as TXT record type (not deprecated SPF type)
Reduce DNS lookups
If you’ve exceeded 10 lookups:
- Use SPF flattening to replace includes with IP addresses
- Remove unused or redundant mechanisms
- Consider SPF macros for dynamic resolution
- Consolidate sending through fewer providers where possible
Flattening requires maintenance — IP addresses change, so flattened records need regular updates.
Handle forwarding failures
SPF can’t survive forwarding by design. Compensate with:
- Implement DKIM (signatures survive forwarding)
- Configure DMARC to pass on DKIM alone
- Use ~all instead of -all so forwarded messages aren’t rejected before DMARC evaluates DKIM
Should you use hard fail or soft fail?
Current industry guidance (as of 2026) favors soft fail (~all) for domains that actively send email. The reasoning:
Why soft fail is recommended
- Accommodates forwarding scenarios where SPF inevitably fails
- DMARC ignores the difference anyway (both count as SPF failure)
- Hard fail can cause early rejection that bypasses your DMARC policy
- Prevents legitimate emails from being rejected before DMARC can evaluate DKIM
When hard fail makes sense
- Parked or defensive domains that send no email
- Domains where you’re absolutely certain all sending sources are documented
- Situations where you want maximum protection against spoofing and accept the deliverability risk
DMARC as the enforcement layer
With DMARC at p=reject, you get the strict enforcement of hard fail without the early-rejection risk. Soft fail + DMARC reject provides:
- SPF failure signals unauthorized senders
- DKIM gets a chance to authenticate forwarded mail
- DMARC enforces the final policy based on both results
This layered approach is why cybersecurity experts increasingly treat DMARC policy as the “real” enforcement mechanism, with SPF and DKIM providing the authentication inputs.
How does SPF failure interact with DKIM and DMARC?
SPF operates alongside DKIM and DMARC in a layered authentication system. Understanding the interaction helps you design records that maximize deliverability.
DMARC requires one to pass
For DMARC to pass, either SPF or DKIM must pass and align. An email can:
- Pass DMARC with SPF only (DKIM fails or isn’t present)
- Pass DMARC with DKIM only (SPF fails)
- Pass DMARC with both (most secure)
DKIM serves as backup when SPF fails due to forwarding or other legitimate scenarios.
Alignment matters
SPF alignment compares the domain in the Return-Path against the domain in the visible From header. Relaxed alignment allows subdomains (mail.example.com aligns with example.com) — strict alignment requires an exact match.
An email can pass the SPF IP check but fail DMARC if alignment fails — the domains don’t match.
When both fail
If SPF and DKIM both fail (or fail to align), DMARC applies your policy:
- p=quarantine: Spam folder
- p=reject: Bounce the message
- p=none: No action, just reporting
Running both SPF and DKIM together provides redundancy. If your DKIM fails and SPF also fails, you have no authentication backup — DMARC will enforce the policy.
SPF failures indicate authentication gaps — monitoring catches them early
SPF failures rarely announce themselves until emails start bouncing or landing in spam. By then, sender reputation damage has already accumulated.
Proactive monitoring reveals:
- DNS lookup counts approaching the limit
- Syntax errors introduced during record updates
- Legitimate sources missing from your SPF record
- Unauthorized IPs attempting to send for your domain
EmailWarmup.com provides the authentication monitoring that catches SPF problems before they compound:
- Reputation monitoring and alerts
- Expert analysis of authentication failures
- 24/7 support from deliverability specialists
- Free email deliverability test across 50+ providers
- DNS authentication verification (SPF, DKIM, DMARC)
Don’t discover SPF failures from bounced campaign emails. Monitor continuously and fix problems while they’re small.
Schedule a free consultation with an email deliverability consultant if you’re having trouble with SPF.
Frequently asked questions
Here are some commonly asked questions about SPF failure:
SPF fail means the receiving mail server checked your domain’s SPF record and couldn’t find the sending IP address listed. The IP that transmitted the email isn’t authorized to send on your domain’s behalf, which signals potential spoofing. Depending on your SPF qualifier and DMARC policy, the email may be rejected, sent to spam, or flagged as suspicious.
Common causes include exceeding the 10-DNS-lookup limit (check your include count), having multiple SPF records for one domain (only one is allowed), or missing a sending source that wasn’t documented. Also, verify the failure isn’t from a forwarded email — SPF inherently fails when messages are forwarded through servers not in your record.
Not necessarily. Hard fail (-all) typically results in rejection. Soft fail (~all) usually means spam folder placement rather than bouncing. If DMARC is configured and DKIM passes, the email can reach the inbox even with SPF failure. The outcome depends on your record configuration, DMARC policy, and the receiving server’s behavior.
Add the third-party’s include mechanism to your SPF record. Each ESP publishes documentation specifying what to add — typically an include: mechanism pointing to their SPF record. After adding, verify your total DNS lookups stay under 10. If you’re at the limit, consider SPF flattening or consolidating sending sources.
Yes. DMARC requires alignment between the Return-Path domain (what SPF checks) and the visible From header domain. If the domains don’t match, SPF passes technically but fails DMARC alignment. The email won’t get DMARC credit for SPF even though the SPF check itself succeeded.
