SPF Check Fails When Include Returns Empty

Why does SPF fail when an include directive returns no DNS records?

You sent an email. It bounced. You checked your SPF record. Everything looked fine. But the error message says "SPF check fails when include returns empty response." You’re not alone. This is a silent but common reason for email delivery issues — and it’s often invisible until it breaks in production.

SPF doesn’t just check your own record. It walks through every include directive like a chain. If one link breaks — if a DNS lookup returns no records — the whole chain fails. The receiving server can’t trust the policy. This isn’t a bug. It’s how SPF is designed: to fail silently but predictably when it can’t verify the full chain. RFC 7208 makes this mandatory.

Key takeaways

SPF validation requires every include directive to resolve to valid DNS records; empty responses cause failure.
An empty response from an include directive results in a soft fail (permerror) or hard fail (fail), depending on the server's policy.
Failure is intentional and defined in RFC 7208: unreachable or invalid includes must be treated as policy violations.

What happens when an include returns an empty DNS response?

If a DNS query for an included domain in your SPF record returns NOERROR but zero records, the SPF validator sees a successful DNS lookup with no policy data. This empty response breaks SPF validation because the system cannot confirm alignment or trust the included domain, leading to a failed SPF check even if the domain exists.

The problem: zero records with NOERROR

When you use include in your SPF record, your email service queries DNS for that domain's SPF record. If the query returns NOERROR but no records — for example, because the domain has no SPF TXT record — it's not a failure. It's a blank answer. Many systems treat this as a valid DNS response, but SPF validators interpret it differently.

Because the validator cannot verify the inclusion policy, it cannot confirm that the domain is authorized to send on your behalf. This uncertainty means the SPF check fails. This is not a bug. It’s how SPF enforcement works by design.

How senders get tripped up

Let’s say your SPF record includes include:mail.example.com, but that domain has no SPF record. The DNS resolver returns NOERROR, a clean result, but no TXT data. You might think, “It’s just missing,” but SPF does not assume trust. The empty response means: “We can’t confirm whether this domain is allowed.”

That lack of confirmation triggers a policy break. Some systems may still allow delivery, but senders with strict filtering — like Gmail or Microsoft — treat this as a red flag. A failed SPF check directly harms sender reputation and inbox placement.

For reference, RFC 7208, the SPF specification, states that an include directive must resolve to a valid SPF record. If it doesn’t, the result is undefined — and in practice, treated as a failure.

It’s not enough to assume that a missing SPF record is harmless. It isn’t. Use tools like MailTester’s email checker to test SPF validation in real time before sending to catch these issues early.

How common is this issue in real-world SPF policies?

Empty responses from included domains in SPF records are uncommon but measurable, primarily appearing in misconfigured or recently decommissioned domains. They usually result from stale DNS records, incorrect TXT record delegation, or brief DNS propagation delays—none of which are rare in large-scale email infrastructures. Even a few minutes of an empty response can trigger SPF failures, especially if the sending domain relies on those includes.

Why empty includes happen in practice

Let’s be clear: most SPFs don’t fail because of a deliberate empty include. Instead, it’s often a side effect of poor DNS hygiene. When a domain is retired or its DNS settings are altered without cleanup, old TXT records—especially those pointing to includes—can return no content. This leaves the SPF chain with a broken link.

You might see this if a company decommissions a partner domain or switches email providers without updating its SPF policy. The include directive still points to the old domain, but that domain now returns no TXT records. Since SPF evaluates each include linearly, an empty result equates to a failure in the chain.

DNS propagation glitches can also cause temporary empty responses. During zone transfers or TTL-based caching, a resolver might query an authoritative server that hasn’t yet synced the latest records. While this usually lasts minutes, it’s enough to break SPF validation if the sending domain’s SPF policy is too strict.

Impact on deliverability

Even short-lived empty responses disrupt SPF validation. If a domain relies on multiple include policies from third-party providers, a single failed lookup can void the entire policy. This means legitimate emails get rejected—not because they’re spam, but because the SPF check couldn’t complete.

Some mail servers interpret a malformed or incomplete SPF record as a soft fail or fail, depending on alignment settings. According to RFC 7208, a permerror (permanent error) occurs if a DNS lookup returns no answer, which can lead to rejection unless the server has a fallback behavior.

Real-world testing confirms that SPF failures due to empty includes are rare in well-maintained domains, but they’re a common red flag in large, fragmented email systems or during migration phases. The issue is avoidable with proactive SPF audits.

Use bulk verification to test your sender domains and identify problematic includes before they impact delivery. Regular checks help you catch stale DNS records early, especially when you're managing multiple partners or third-party email services.

How to detect if an SPF include is returning an empty response

You can detect an empty SPF include response by querying the DNS TXT record of the included domain using tools like dig or nslookup. A NOERROR response with zero records means the domain exists but has no SPF or TXT records, or the record is malformed. This breaks SPF validation and can cause delivery failures. Always verify the actual DNS behavior, not just the syntax of your SPF record.

Step-by-step validation process

Identify the included domain in your SPF record (e.g., "include:_spf.google.com"). This is the domain whose DNS you need to check.
Use dig to query the TXT record from your terminal: dig TXT _spf.google.com. A clean NOERROR response with no listed records indicates an empty answer.
Check for DNS errors like NXDOMAIN (domain doesn’t exist) or SERVFAIL (server failure), which are different from empty responses but both break SPF validation.
Verify the domain exists with a simple dig A domain.com to ensure it’s not a typo or non-existent domain.
Examine the response structure — missing records, malformed syntax (like a missing quote), or an incorrectly formatted TXT value can all appear as empty or invalid to SPF parsers.
Test across multiple DNS resolvers using online tools to rule out temporary resolver issues. A consistent empty result across providers confirms the issue.

Common causes of empty SPF includes

Empty responses often stem from third-party providers not publishing valid SPF records, domains with misconfigured DNS, or records that were removed. For example, some CDNs or email platforms may change their SPF policies without notification. If the included domain returns no TXT records despite existing, SPF will treat the include as invalid and fail.

The 6 steps described in “Step-by-step validation process”, in order.

According to RFC 7208, SPF parsers must reject includes that return no records as non-authoritative. This means you can’t assume an include is safe just because it’s listed — it must actively return valid data.

Always test each included domain as a standalone check. Tools like MailTester’s email checker can help validate domain-level SPF records as part of a broader deliverability audit.

SPF checks fail with 'empty include' — what's the real impact?

When an SPF check fails because an include directive returns an empty response, receivers treat it as a softfail or fail. This reduces inbox placement, especially for high-volume senders. Over time, repeated failures degrade sender reputation, triggering filters that delay delivery or flag messages as spam. Even a single flawed include can hurt deliverability if your domain is under scrutiny.

How receivers interpret empty include responses

SPF policies are evaluated in sequence. If an include directive returns no records or an empty result, the SPF check fails. Most receivers mark this as a softfail by default — not outright rejection, but a red flag. According to the SPF specification (RFC 7208), this is considered a failure state, meaning the policy cannot be satisfied.

Some receivers act on softfails by reducing message priority or placing them in lower-priority folders. Others, like Gmail and Microsoft’s filtering systems, may apply additional scrutiny. If your domain has a pattern of such failures, it can signal poor mail hygiene, even if the message is technically valid.

Why repeated failures matter over time

A single softfail isn't catastrophic — but it accumulates. High-volume senders, especially in marketing or transactional workflows, face greater risk. Repeated SPF failures, even from one misconfigured include, can trigger sender reputation penalties. This affects not just your own messages, but those sent from shared IPs or third-party platforms.

Mail providers use reputation signals heavily. If your domain consistently shows SPF issues, even minor ones, it may face slower delivery, higher bounce rates, or placement in spam folders. This isn’t about a one-time bounce — it’s about long-term trust.

You can catch this before sending. Use an email checker to test your SPF record for includes that return no results. Tools like MailTester validate the full chain of SPF lookups and flag empty responses in real time. They also test deliverability across inboxes — including major providers like Gmail and Outlook — so you can see if your messages land in the inbox or get deferred.

When an SPF include directive returns an empty DNS response, the SPF check fails silently — which means messages from that domain are at high risk of being rejected or marked as spam. MailTester’s real-time verification API catches these issues by testing each email address against active DNS policies, flagging addresses from domains with broken or empty SPF includes before they’re sent. This prevents bounce-backs, protects sender reputation, and keeps your campaigns from being blocked.

How SPF failures happen in practice

SPF (Sender Policy Framework) relies on public DNS records to define which servers can send email for a domain. When a domain uses the include directive to reference another domain’s SPF record, and that referenced domain returns no record — or an empty response — the SPF evaluation fails. This happens more often than you’d expect, especially with third-party services or poorly maintained configurations. An empty response doesn’t mean "no policy" — it means the policy can’t be loaded, which triggers a fail-open behavior in some mail servers, leading to delivery failures.

Let’s say your list includes an address like [email protected]. If yourcompany.com includes include:spf.3rdparty.com, but spf.3rdparty.com returns no record — you’re left with a broken SPF chain. Email servers may treat this as a failure, even if the sender is legitimate. This isn’t a rare edge case. According to RFC 7208, a missing or malformed include should result in a hard fail during SPF evaluation.

How MailTester flags and blocks risky addresses

MailTester’s real-time API doesn’t just check syntax. It queries DNS in real time — including all include directives — to see if they return valid, non-empty records. If any include returns no response, MailTester marks the address as risky or invalid based on the depth and impact of the failure. This gives you a clear signal before you send.

For example, if include:mailing-service.net returns no SPF record, MailTester will flag the entire address as problematic. These are not guesswork judgments — they’re based on explicit DNS behavior and real-time checks. You’ll catch domains with broken policies before they damage your sender reputation.

If you're running campaigns on a large list, use this to your advantage: bulk verify your list and filter out high-risk addresses before sending. You can then use our verification API to integrate checks directly into your sending workflow. Even testing a single address with our email checker shows you the full DNS behavior, including SPF issues, in seconds.

Use MailTester to verify SPF health when cleaning email lists

Running bulk list verification with MailTester exposes email addresses tied to domains with flawed SPF policies—like those where an include directive returns an empty response. These misconfigurations can trigger SPF failures, leading to deliverability drops even if the mailbox exists. Use the 'risky' verdict to surface such cases before you send.

Identify and act on SPF configuration issues

Upload your mailing list to MailTester’s bulk email verification tool to test all addresses at scale.
Review the results: look for the 'risky' verdict, which flags addresses where SPF checks fail due to malformed or missing policies, including empty include responses.
Check the SPF record of domains flagged by MailTester using tools like MXToolbox to validate the configuration independently.
Empty include directives—such as include:example.com when no TXT record resolves—can cause SPF checks to fail silently. This is common in inherited or poorly maintained DNS.
Remove or isolate addresses from domains flagged with 'risky' SPF status to avoid being blocked by receivers that enforce strict SPF validation.

Prevent deliverability issues before they happen

SPF failures aren’t always visible at first glance—some recipients receive messages anyway, but others reject them outright. This inconsistency leads to poor inbox placement and reputation damage over time.

Use MailTester’s real-time verification API to pre-validate new signups, catching SPF issues at point of entry. This prevents bad data from entering your system in the first place.

For high-volume senders, integrate MailTester with platforms like Mailchimp, HubSpot, or Klaviyo via the built-in integrations to automate cleanup. You don’t need to manually scrub lists when every new address gets tested.

SPF is not just a technical detail—it’s part of your sender reputation. A single misconfigured domain can taint your entire domain’s deliverability score. Regular verification helps you stay ahead of these invisible risks.

What SPF records should you check to prevent empty response issues?

If an SPF include directive returns no response, your SPF check fails. To prevent this, verify that every domain listed in your SPF record’s include directive actually exists, has a valid SPF TXT record starting with v=spf1, and isn’t misconfigured or unreachable. A single broken include can invalidate your entire policy.

Check Every Included Domain

Review each include directive in your SPF record. Identify every domain listed—like include:_spf.google.com or include:spf.example.com. These domains must be actively maintained and return a valid TXT record.
Validate that the included domain has a proper SPF TXT record. Use a DNS lookup tool to confirm the domain returns a TXT record starting with v=spf1. If it returns nothing or starts with something else (like v=spf2.0), the include fails silently.
Verify the included record has no syntax errors. A missing space, extra quote, or invalid mechanism (like ip4: without a CIDR) can cause parsing failure. Even one typo breaks the entire policy.
Test each include using a DNS checker or MailTester’s API. Tools like MXToolbox or RFC 7208 (the SPF specification) help verify responses. MailTester’s API can batch-check records across your policy chain, catching empty or invalid includes before they impact deliverability.
Update or remove broken includes. If a domain no longer uses SPF or has a misconfigured record, either remove the include or replace it with a valid one. Always test your updated policy with inbox placement tools to confirm it resolves.

Why This Matters

SPF checks run on every email you send. If an include returns an empty or malformed response, the SPF check fails outright. Mail servers treat this as a hard failure—your email may land in spam or be rejected. This problem is commonly seen with outdated vendor records, misconfigured third-party providers, or domains with no TXT record at all.

Let’s be clear: an empty include isn’t just a warning. It’s a policy-level error that undermines your sender reputation. Regular verification of every include is not optional. Use tools that check the actual DNS response, not just a static list. With MailTester’s bulk verification, you can audit your entire list of included domains at once—no guesswork, just reliable results.

Can empty responses be caused by third-party services or providers?

Yes — if your SPF record includes a domain from a provider like SendGrid, Mailgun, or HubSpot that hasn’t published a valid SPF record, the lookup returns an empty response. This often happens when a provider’s domain is removed from your account but the SPF include remains, or during onboarding, migration, or domain deactivation. You’ll see a soft fail or neutral result in SPF checks, which can still break your sender reputation.

Common causes in practice

Let’s say you’ve added include:_spf.sendgrid.net to your SPF record. If SendGrid hasn’t published a valid SPF record for that domain — or if their record is temporarily invalid — your SPF check will return no data. An empty response isn’t a failure in the usual sense, but it breaks SPF alignment, and many systems treat it as a soft fail due to the lack of a definitive policy.

This issue is most common when migrating from one email service provider to another, or when deactivating domains without reviewing your SPF record. Even if your account is closed, the include remains unless manually removed. The domain might still be in use elsewhere, but if its SPF record is missing or malformed, it can silently break your own email authentication.

According to the IETF's RFC 7208, SPF records are authoritative only when published and properly formatted. If a domain doesn’t publish a record, the lookup returns nothing — not even a "no match." That empty result is what triggers problems in automated checks.

How to fix and test it

Review every include in your SPF record. If the included domain doesn’t resolve to a published SPF record, you can’t trust it. Tools like MXToolbox or Spamhaus can help diagnose if a domain’s SPF record is published and valid.

Use MailTester’s email checker to test individual domains and catch issues early. You can also run a bulk verification to scan large lists for risky senders. These tools check SPF, DMARC, and other auth records in real time, including responses to includes — so you won’t get caught by empty records during outbound sends.

Don’t assume a provider’s domain is safe just because it’s used in your setup. Always verify that the included domain actively publishes and maintains a proper SPF record — or remove the include entirely.

Why fixing empty SPF includes matters for deliverability

If your SPF check fails because an include directive returns an empty response, your emails risk being filtered, delayed, or blocked entirely—even if the failure is temporary. This kind of instability signals poor sender hygiene, which inbox providers like Gmail and Outlook track closely. Even a single flaky SPF record can trigger spam scoring, especially at scale. Regularly verifying your sender policy with tools like MailTester’s email checker helps catch these issues before they hurt delivery.

SPF instability harms sender reputation

When SPF validation fails due to an empty include, mail servers don’t know if the message truly came from an authorized source. Even a brief or intermittent failure can be flagged by systems that monitor alignment and consistency. High-volume senders with inconsistent SPF records are more likely to be throttled or marked as suspicious by receiving providers. This isn’t just about one email—it’s about patterns over time. Consistent policy violations, even minor ones, accumulate into reputational debt.

Proactive verification prevents downstream issues

Let’s be clear: you don’t want to discover SPF issues only after email volume drops or delivery rates fall. Proactively checking your SPF records—especially those relying on include statements from third-party providers—ensures they resolve correctly and return valid data. Tools like MailTester’s bulk verification or real-time API can scan multiple domains for malformed or empty includes before they impact your campaign. Even a small number of invalid records can cause systemic issues when scaled.

The underlying principle is simple: delivery depends on trust, and trust is built through consistency. Empty SPF includes break that trust by introducing uncertainty. While RFC 7208 (which defines SPF) doesn't require a strict response format, real-world systems expect predictable, valid results. A poorly configured include may not fail outright, but it undermines the validation chain. This is why fixing empty includes isn’t a technical nicety—it’s essential for reliable email delivery.

How to avoid SPF check failures caused by include directives

SPF check failures when include returns an empty response happen when your policy references a domain that lacks an SPF record or returns no valid policy. This breaks the chain and causes SPF validation to fail.

Best practices for SPF configuration

Remove any include directives that point to domains with no SPF records or empty responses.
Replace old or deprecated includes with verified, current SPF policies from your email service providers.
Always test your complete SPF policy using an SPF validator before deployment to catch syntax issues or broken includes.

Even small misconfigurations in SPF policies can lead to email rejection. Validating your policy ensures consistent deliverability.

Sources

The number of top domains at DMARC enforcement grew from 233,249 in 2023 to 411,935 in 2026 — a 77% increase driven largely by mailbox-provider sender mandates. — EasyDMARC 2026 DMARC Adoption & Enforcement Report (2026)
Google reported 265 billion fewer unauthenticated messages sent to Gmail users in 2024 — a 65% reduction — after its bulk-sender rules took effect, with 500,000+ top domains publishing DMARC records in response. — Google (via MailOver bulk-sender requirements guide) (2024)

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Frequently asked questions

What does 'SPF check fails when include returns empty response' mean?

The SPF policy can't verify a domain listed in an include directive because that domain’s DNS returns no records, even though the query was successful. This causes the check to fail.

Can an empty DNS response really break SPF?

Yes, according to RFC 7208, an unresolvable or empty include causes the SPF evaluation to fail, resulting in a soft fail or hard fail.

How long do empty DNS responses last?

They can persist from minutes to days, depending on TTL settings and whether the domain was deleted or misconfigured.

Does MailTester check SPF policies?

Yes, MailTester checks email addresses by validating their domain's DNS records, including SPF, DKIM, and MX, and flags risky or invalid recipients.

Can a single empty include break my entire SPF policy?

Yes — even one empty or unresolvable include breaks the evaluation chain, causing the entire policy to fail.

Are empty includes common?

Not common, but they do occur, especially with third-party service integrations or outdated DNS records.

What happens if I keep sending to addresses with broken SPF?

Your emails may be marked as spam, delayed, or rejected by receivers that enforce strict SPF checks.

Can I fix this by updating my SPF record manually?

Yes — remove or replace the include directive pointing to a domain with an empty response and use a valid, active domain instead.

How do I test my SPF policy before sending?

Use online SPF validators or MailTester’s real-time API to test your policy and verify if any includes return empty responses.

Does MailTester warn about empty include responses?

It doesn't analyze SPF policies directly, but it detects and flags email addresses from domains with broken SPF or empty DNS responses during verification.

Can disposable domains cause SPF check failures?

Yes, disposable domains often lack SPF policies or return empty DNS responses, triggering SPF failures when included.

Does a successful DNS query without records mean the domain is invalid?

Not necessarily — it means the domain exists but has no TXT record. It may still be valid, but SPF checks will fail if the policy relies on it.