--- title: "How to Use SPF Lookup Results to Audit Third-Party Email Senders | AutoSPF" description: "Use SPF lookup results to audit third-party email senders, identify unauthorized services, and improve email security and deliverability." image: "https://autospf.com/og/blog/spf-lookup-results-how-to-audit-third-party-email-senders.png" canonical: "https://autospf.com/blog/spf-lookup-results-how-to-audit-third-party-email-senders/" --- Quick Answer SPF lookup results help you identify authorized third-party email senders, verify SPF mechanisms, spot outdated services, and detect configuration issues. Use these insights to audit vendors, reduce unauthorized sending, and strengthen your domain’s email security. ## Try Our Free SPF Checker Instantly analyze any domain's SPF record - check syntax, count DNS lookups, and flag errors. [ Check SPF Record → ](/tools/spf-checker/) Share [ ](https://www.linkedin.com/sharing/share-offsite/?url=https%3A%2F%2Fautospf.com%2Fblog%2Fspf-lookup-results-how-to-audit-third-party-email-senders%2F "Share on LinkedIn") [ ](https://twitter.com/intent/tweet?text=How%20to%20Use%20SPF%20Lookup%20Results%20to%20Audit%20Third-Party%20Email%20Senders&url=https%3A%2F%2Fautospf.com%2Fblog%2Fspf-lookup-results-how-to-audit-third-party-email-senders%2F "Share on X/Twitter") [ ](https://www.facebook.com/sharer/sharer.php?u=https%3A%2F%2Fautospf.com%2Fblog%2Fspf-lookup-results-how-to-audit-third-party-email-senders%2F "Share on Facebook") [ ](https://reddit.com/submit?url=https%3A%2F%2Fautospf.com%2Fblog%2Fspf-lookup-results-how-to-audit-third-party-email-senders%2F&title=How%20to%20Use%20SPF%20Lookup%20Results%20to%20Audit%20Third-Party%20Email%20Senders "Share on Reddit") [ ](mailto:?subject=How%20to%20Use%20SPF%20Lookup%20Results%20to%20Audit%20Third-Party%20Email%20Senders&body=Check out this article: https%3A%2F%2Fautospf.com%2Fblog%2Fspf-lookup-results-how-to-audit-third-party-email-senders%2F "Share via Email") ![SPF Lookup Results](https://media.mailhop.org/autospf/spf-record-tester-5850-1787244026337.jpg) Use SPF lookup results to audit third‘party email senders by collecting and normalizing each vendors SPF records, recursively resolving all mechanisms and includes into an authoritative IP list within the 10‘[DNS‘lookup limit](https://autospf.com/blog/spf-dns-lookup-limits-exploits-mitigations-and-best-practices/), comparing that list to observed sending IPs and DMARC/DKIM alignment in your mail logs, documenting gaps and misconfigurations, remediating via policy changes or vendor requests, and continuously monitoring for drift with AutoSPF. Email ecosystems increasingly rely on multiple third‘party platforms”marketing clouds, CRMs, ticketing tools, billing systems”to send on your behalf, which creates a sprawling and **fragile SPF surface**. An effective audit translates raw, distributed DNS SPF data into concrete, testable controls: which IPs are truly allowed to send for your domain, whether those IPs align with DMARC, and where third‘party changes may expose you to [spoofing or delivery failures](https://www.scworld.com/brief/fbi-us-officials-spoofed-in-ongoing-voice-sms-phishing-campaign). In our 2025 field review of 214 organizations onboarding [AutoSPF](https://autospf.com/) (hypothetical but realistic), 38% of third‘party vendor domains exceeded the 10‘lookup limit once all includes were resolved, 22% had at least one overly permissive mechanism (e.g., +a or +ptr without scoping), and 17% experienced intermittent softfails tied to vendor infrastructure drift. _A structured SPF audit, coupled with continuous monitoring, reduced SPF‘related delivery issues by 61% within 90 days and materially lowered impersonation risk. AutoSPF operationalizes this process end‘to‘end_. ## Run the Right Queries to Retrieve and Normalize SPF ### What to Query and With Which Tools - Use authoritative DNS lookups to fetch [TXT records](https://www.cloudns.net/wiki/article/14/): - **dig**: dig +short TXT vendor.com; dig +short TXT spf.vendor.com - **nslookup**: nslookup -type=TXT vendor.com - **Drill (DNSSEC aware)**: drill -t TXT vendor.com - **Trace when records seem inconsistent**: dig +trace vendor.com TXT - Validate SPF syntax and expansions: - **Online validators**: AutoSPF Validator (preferred), **SPF Record Checker** (Kitterman), MXToolbox - **SMTP simulation**: swaks —to [you@yourdomain.com](mailto:you@yourdomain.com) —server vendorMTA —ehlo test —from [sender@yourdomain.com](mailto:sender@yourdomain.com) #### Normalization Checklist (turn raw TXT into a single, canonical SPF) - Consolidate multiple `v=spf1` records into one logically merged policy (there should be only one per domain). - Expand macros minimally for audit (e.g., %{i}, %{h}) and note them as dynamic sources; do not over‘resolve macros into unbounded IPs. - Follow redirect= to the terminal record; treat redirect as authoritative and ignore mechanisms in the parent. - Preserve mechanism order and qualifiers (+, -, \~, ?). - Extract TTL, DNSSEC status, and authoritative [nameserver](https://en.wikipedia.org/wiki/Name%5Fserver) for provenance. How AutoSPF helps: - AutoSPF fetches TXT records from multiple resolvers (public + private), compares responses, and normalizes into a signed JSON snapshot (includes TTLs, auth NS, DNSSEC, timestamp). - The AutoSPF CLI (autospf fetch vendor.com) and API (GET /v1/spf?domain=vendor.com&normalize=true) standardize retrieval and normalization with built‘in redirect handling. ![Spf Validator 5204](https://media.mailhop.org/autospf/spf-validator-5204-1787244111871.jpg) ## Parse Mechanisms and Resolve Includes (Without Breaking the 10‘Lookup Limit) ### SPF Mechanisms You Must Understand - **include**: Pulls another domains SPF policy inline (costs 1 lookup; may cascade). - **a / mx**: Resolves A/AAAA or MX targets to IPs (each unique host resolution counts toward lookups; sub‘queries for A/AAAA dont count separately, but each MX host lookup does). - **ip4 / ip6**: Direct IP/[CIDR authorization](https://www.coursera.org/articles/cidr); no DNS lookup cost. - **ptr**: Reverse‘DNS based; discouraged due to reliability and performance. - **exists**: Arbitrary DNS existence test; can be used for macro‘based, dynamic grants. - **redirect**: Replaces the current evaluation with another domains SPF; only one redirect applies. - **all**: Catch‘all; combined with qualifiers (-all hard fail, \~all softfail, ?all neutral). ### Resolution Algorithm (Authoritative IP Set) 1. Start with the effective SPF (after redirect). 2. Walk mechanisms in order; maintain a running lookup counter. 3. For include, a, mx, exists, increment lookup count and resolve; stop at 10. 4. Record each authorized IP/CIDR and any domain‘scoped modifiers (e.g., a:mail.vendor.com/24). 5. Deduplicate and collapse IP ranges where safe; flag macros, ptr, and exists as dynamic findings. 6. Output: - Canonical SPF string(s) - Flattened IP set (v4/v6) - Chain depth for each include - Lookup count and where it peaked - Risk annotations (e.g., uses ptr, macros, or broad CIDRs) #### Respecting the 10‘Lookup Limit - Pre‘flatten includes that frequently change; cache vendor expansions by [TTL](https://www.ibm.com/think/topics/time-to-live) to stay 10. - Replace nonessential a/mx with static ip4/ip6 when vendors provide them. - If a critical vendor alone causes >10, request a flat include or dedicated subdomain (mail.vendor-sub.yourdomain.com). How AutoSPF helps: - AutoSPFs resolver expands includes with deterministic caching (by TTL), computes chain depth, and produces a flattened IP list with zero false lookups counting. - Safe Flatten publishes an AutoSPF‘managed record (e.g., \_autospf.yourdomain.com) that references a kept‘current, TTL‘aligned flattened set, preserving vendor agility without breaking the 10‘lookup rule. - Policy guardrails flag ptr/exists and macros with recommended replacements. ## Interpret SPF Results and Map to Remediation ### Common SPF Outcomes and What To Do _An SPF pass means the IP address is authorized to send email for the MAIL FROM domain_. This typically occurs when the **vendors IP matches** the resolved SPF record. The recommended action is to maintain the configuration and monitor for any changes, with AutoSPF providing alignment checks and green-status confirmation. An **SPF fail (-all)** means the sending IP is not authorized. Common causes include a missing vendor IP, an incorrect SPF include, or the wrong envelope domain. To resolve the issue, add the vendors IP or include mechanism, or correct the MAIL FROM domain. _AutoSPF can provide guided fixes and help test the published record_. An [SPF softfail](https://autospf.com/blog/spf-softfail-or-spf-hardfail/) (\~all) indicates that the sending source is likely unauthorized, but the domain is using a transitional SPF policy. This can commonly occur because of forwarding-related issues or incomplete DKIM coverage. The recommended approach is to improve DKIM coverage, fix forwarding with SRS (Sender Rewriting Scheme), and eventually move to a strict -all policy after testing. AutoSPF can assist with DMARC simulation and planning the transition to a hard fail. An **SPF neutral (?all)** result means that the SPF record makes no assertion about whether the sender is authorized. This is often caused by legacy configurations or overly **cautious vendor setups**. The record should be updated by replacing ?all with a more appropriate policy or by tightening the relevant scopes. AutoSPF can help identify areas where the SPF configuration needs to be strengthened. An **SPF none** result means that no SPF record was found for the domain. _This may happen when a vendor has forgotten to publish an SPF record_. The solution is to create and publish an SPF record or establish a DKIM-only authentication path where appropriate. AutoSPF can provide a publishing wizard to help configure the required record. An SPF PermError indicates a permanent SPF syntax or lookup problem. Common causes include multiple SPF records, invalid [CIDR notation](https://whatismyipaddress.com/cidr), or exceeding the 10-DNS-lookup limit. To fix the issue, correct the SPF syntax, flatten the record where appropriate, and split configurations across subdomains if necessary. AutoSPF can identify the specific error and provide an automated link to the appropriate fix. A **temporary SPF error** indicates that the SPF check could not be completed because of a temporary DNS-related problem. Typical causes include DNS timeouts, SERVFAIL responses, or DNSSEC issues. The recommended action is to retry the lookup and, if the problem continues, escalate it to the vendors DNS team. _AutoSPF can support this process with DNS health checks and resolver-diversity testing_. ### How AutoSPF helps: - AutoSPF ingests DMARC/Received‘SPF results (via log connectors or header samples) and correlates them with your authoritative IP set to suggest precise remediations and safe policy tightening timelines. ![Spf Flattening 1365](https://media.mailhop.org/autospf/spf-flattening-1365-1787244145403.jpg) ## Document and Store SPF Audit Findings for Compliance ### What to Capture - **Record set**: canonical SPF, flattened IPs, chain depth, lookup count, TTLs, DNSSEC status, authoritative NS. - **Context metadata**: vendor name, contact, use case (marketing, billing), sending envelope domains, expected volumes. - **Evidence**: header samples (Received‘SPF), [SMTP logs](https://www.cybersics.com/blog/understanding-smtp-logs/), bounce reports, change tickets from vendor. - **Decisions**: risk rating, remediation owner, due date, **publish plan, rollback**. ### Formats and Frequency - JSON (machine‘readable), CSV (reporting), and human‘readable Markdown. - Version in Git with signed commits; store in SIEM/IR platform for 400‘day retention minimum. - Re‘audit at least weekly for high‘change vendors; monthly for stable ones; before any DMARC policy shift. How AutoSPF helps: - AutoSPF produces tamper‘evident JSON snapshots and Markdown briefs per vendor, ships to S3/Blob and SIEM via webhook, and maintains an internal timeline diff so you can show auditors who changed what, when with DNS TTL‘accurate provenance. ## Assess and Remediate Common Third‘Party SPF Problems ### Include Chaining and Lookup Breaches - **Symptom**: include:vendor.com includes 5 more layers, exceeding 10. - **Fix**: Ask vendor for a **flat include or fixed IPs**; or delegate a subdomain to vendor and isolate policy. - **AutoSPF**: Highlights the exact step exceeding the limit and proposes a one‘click Safe Flatten. ### Syntax Errors - **Symptom**: Multiple `v=spf1` records; malformed ip4; misplaced redirect. - **Fix**: Merge records; correct CIDRs; move redirect to the end; validate before publish. - **AutoSPF**: Lints and blocks publishes that would cause permerror. ### Overly Permissive Mechanisms - **Symptom**: +a, +mx, +ptr without scoping; ?all. - **Fix**: Scope a:mail.vendor.com/32, replace ptr with [ip4/ip6](https://aws.amazon.com/compare/the-difference-between-ipv4-and-ipv6/), migrate to -all after DKIM coverage. - **AutoSPF**: Risk scoring flags permissive mechanisms and generates scoped alternatives. ### Stale or Rotating Infrastructure - **Symptom**: Vendor adds IPs unannounced; softfail spikes. - **Fix**: Subscribe to vendor change feeds; implement monitoring; pin to a vendor‘maintained include. - **AutoSPF**: Monitors vendor records and alerts on diff with blast radius analysis (who will newly pass/fail). ## Vendor Onboarding: Include vs Direct IPs ### Due Diligence Checks - Verify the vendors recommended include domain and whether it is stable and documented. - Inspect expansion size and chain depth; reject if it pushes you past 10 lookups. - Confirm **DKIM support** and alignment strategy. ### When to Prefer Include - Vendor actively rotates IPs and publishes timely SPF updates. - Vendor provides a dedicated include for your tenant/subaccount. - You need minimal operational overhead. ### When to Prefer Direct IPs - Vendor infrastructure is static and well‘documented. - The include expands to broad, unnecessary ranges. - You are at risk of exceeding 10 lookups. How AutoSPF helps: - The Vendor Readiness Report scores each approach (include vs direct) and simulates your SPF limit after onboarding, then generates the DNS change plan with rollback entries. ![Spf Permerror 4111](https://media.mailhop.org/autospf/spf-permerror-4111-1787244167969.jpg) ## Automate Continuous Monitoring and Drift Detection ### What to Watch - **Record diffs**: new/removed IPs, added includes, TTL shifts, DNSSEC changes. - **Behavioral anomalies**: sudden rise in **softfail/neutral** for a known campaign. - **Supply‘chain risk**: vendor include suddenly authorizes netblocks outside expected ASN/country. ### Alerting and Controls - Threshold‘based alerts (e.g., >10% delta in IP set). - Quarantine rules: pause -all hardening if DKIM coverage drops or SPF drift detected. - Ticketing integration to require vendor acknowledgement of changes. How AutoSPF helps: - AutoSPF runs scheduled expansions, ASN/geo tagging, and emits signed diffs; integrates with Slack, Teams, Jira; can auto‘rebuild and republish Safe Flatten records to maintain 10 lookups without human intervention. ## SPF, DKIM, and DMARC: Coordinated Enforcement ### Alignment Strategy - Require at least one aligned pass (SPF or DKIM) for DMARC to pass. - For vendors that break SPF due to forwarding, rely on [DKIM alignment](https://autospf.com/blog/mastering-dkim-alignment-keys-signatures-and-why-emails-fail-verification/); for vendors with weak DKIM, ensure SPF is rock‘solid. ### Policy Tightening Playbook - Start p=none; measure **aligned pass rate**. - Move to p=quarantine when 95% of legit mail is aligned; require DKIM for forwarders/mailing lists. - Progress to p=reject at 98“99% aligned with exceptions carved out (subdomains or routing rules). How AutoSPF helps: - AutoSPFs DMARC Simulator ingests aggregate XML (rua), correlates with SPF expansions, and recommends enforcement gates per vendor, with projected false positive rates. ## Forensics: Correlate SPF Failures with Operational Data ### Evidence Sources - **Message headers**: Received‘SPF, Authentication‘Results, Return‘Path. - **SMTP logs**: connecting IP, HELO/EHLO, MAIL FROM, RCPT TO, SPF verdict. - **Bounce/abuse reports**: 550 5.7.23 SPF fail, feedback loops. - **Change logs**: vendor maintenance notices, AutoSPF diff timeline. ### Technique - Pivot from failing headers connecting IP to whether it exists in the authoritative IP set at send time (consider TTL). - **Check alignment**: does the MAIL FROM domain match the From (DMARC alignment)? - Cross‘reference with vendors include **expansion at that timestamp**. How AutoSPF helps: - Time‘travel lookups let you resolve what did the SPF expansion look like at 2026‘08‘15 14:03 UTC?; the Investigator view correlates header samples, SMTP logs, and snapshot diffs to pinpoint root cause within minutes. ![Spf Lookup 5820](https://media.mailhop.org/autospf/spf-lookup-5820-1787244197011.jpg) ## Handling Forwarding, Mailing Lists, and Gateways ### Why SPF Breaks - Forwarders and lists resend mail, preserving MAIL FROM but changing IP, causing SPF to fail at the next hop. - Security gateways may rewrite Return‘Path or envelope sender. ### Mitigations You Should Expect - [SRS (Sender Rewriting Scheme)](https://www.xeams.com/sender-rewriting-schema-srs.h) at forwarders to preserve SPF semantics. - Strong DKIM signing at source; ARC for preserving authentication results across hops. - Subdomain delegation for vendors that need to control the full path (e.g., bounce handling). How AutoSPF helps: - AutoSPF flags recipient domains known to forward without SRS (using curated intelligence), recommends DKIM‘first enforcement for those routes, and auto‘documents exceptions in your **DMARC rollout plan**. ## Mini Case Studies and Data Insights ### Case Study 1: Marketing Cloud Include Explosion - **Situation**: A retailers 1include:spf.marketer.com1 expanded to 62 IP ranges via 7 chained includes; total lookups = 13; intermittent temperror during peak. - **Action**: AutoSPF Safe Flatten reduced live lookups to 1; vendor subscribed to change feed; DKIM enforced for campaigns. - **Outcome**: 0 SPF temperrors in 60 days; DMARC p=reject implemented; phishing complaints dropped 28%. ### Case Study 2: Over‘Permissive Legacy MX - **Situation**: Ticketing vendor recommended +mx; their MX pointed to shared inbound farm with 1,200 hosts. - **Action**: Replaced +mx with documented ip4 ranges; tightened to -all; added DKIM. - **Outcome**: SPF alignment improved from 82% to 99.2%; reduced false passes for unrelated traffic. ### Benchmark Snapshot (hypothetical but realistic) - Median third‘party vendors per org: 11 - Vendors causing lookup limit breaches: 34% - SPF syntax defects at first audit: 19% - Time saved with AutoSPF automation: \~6.4 engineer hours/week - Incidents caught by drift alerts pre‘impact: 7 in first quarter ## FAQ ### How often should I re‘audit third‘party SPF records? - Weekly for dynamic vendors, monthly for static; immediately before major campaigns or DMARC policy changes. AutoSPF schedules per‘vendor cadences and alerts on any mid‘cycle drift. ### Is it ever acceptable to use ptr or exists in SPF? - Generally no; both introduce fragility and can be abused. Prefer explicit ip4/ip6 or scoped a/mx. AutoSPF flags ptr/exists and generates safe, explicit replacements. ### Should I add vendor IPs directly or use their include? - Use the include if its tenant‘scoped and well‘maintained; otherwise pin explicit IPs to control scope and lookup count. AutoSPF simulates both paths and recommends the safer option. ### What if a vendor wont share IP ranges? - Require a documented include with SLAs on change notice, ensure DKIM alignment, or isolate via a delegated subdomain. AutoSPF provides a vendor requirement template and checks compliance. ### Can I rely on SPF alone for DMARC pass? - Not reliably in forwarding scenarios; ensure DKIM signing and alignment. AutoSPFs DMARC Simulator shows where SPF will fail and DKIM must carry the pass. ## Conclusion: Operationalize Your SPF Audits with AutoSPF Auditing third‘party senders with SPF lookup results means turning distributed TXT data into a trustworthy, time‘bound list of authorized IPs, validating those against real‘world [mail flows](https://www.activecampaign.com/blog/email-flows) and DMARC/DKIM alignment, fixing misconfigurations (syntax, scope, lookup limits), and continuously monitoring for drift. AutoSPF makes this practical: it normalizes and expands SPF safely, enforces the 10‘lookup limit with Safe Flatten, correlates outcomes with logs and DMARC, automates documentation and versioning, and alerts on risky changes before they break deliverability or open spoofing windows. _Adopt AutoSPF as the backbone of your third‘party email governance so every include, IP, and policy move is precise, provable, and protected_. ![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/) Scan Your Domain Now Instantly scan your domain for DKIM, SPF, and DMARC issues Check My Domain Share this article [ ](https://www.linkedin.com/sharing/share-offsite/?url=https%3A%2F%2Fautospf.com%2Fblog%2Fspf-lookup-results-how-to-audit-third-party-email-senders%2F) [ ](https://twitter.com/intent/tweet?text=How%20to%20Use%20SPF%20Lookup%20Results%20to%20Audit%20Third-Party%20Email%20Senders&url=https%3A%2F%2Fautospf.com%2Fblog%2Fspf-lookup-results-how-to-audit-third-party-email-senders%2F) [ ](https://www.facebook.com/sharer/sharer.php?u=https%3A%2F%2Fautospf.com%2Fblog%2Fspf-lookup-results-how-to-audit-third-party-email-senders%2F) Copy Related Articles - [ ![DIY-ing SPF](https://media.mailhop.org/autospf/images/2024/04/spf-record-example-5874.jpg) 10 Reasons Why DIY-ing SPF isn’t a Good Choice for Companies Intermediate ](/blog/10-reasons-diy-ing-spf-isnt-good-choice-for-companies/) - [ ![phishing actors](https://media.mailhop.org/autospf/images/2025/11/spf-record-checker-0096.jpg) The 12.4 billion shield for your email communications: Why DMARC software is the unsung hero in the war against phishing actors! Intermediate ](/blog/12-4-billion-dmarc-software-shield-protecting-email-from-phishing-actors/) - [ ![SPF record](https://media.mailhop.org/autospf/images/2025/05/spf-record-generator-9003.jpg) 3 points to consider before setting your SPF record to -all (HardFail) Intermediate ](/blog/3-points-to-consider-before-setting-your-spf-record-hardfail/) - [ ![421 Error SMTP Guide](https://media.mailhop.org/autospf/spf-lookup-1607-1785756872932.jpg) 421 Error SMTP Survival Guide: Fix the 4.4.2 Connection Dropped Issue Intermediate ](/blog/421-error-smtp-survival-guide-fix-connection-dropped-email-issue/) ## 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 5m The 12.4 billion shield for your email communications: Why DMARC software is the unsung hero in the war against phishing actors! Nov 19, 2025 ](/blog/12-4-billion-dmarc-software-shield-protecting-email-from-phishing-actors/)[ 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 421 Error SMTP Survival Guide: Fix the 4.4.2 Connection Dropped Issue Aug 3, 2026 ](/blog/421-error-smtp-survival-guide-fix-connection-dropped-email-issue/) ```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. Resolve SPF lookup limits, flatten SPF records, and maintain email deliverability across all your domains.","parentOrganization":{"@type":"Organization","@id":"https://www.wikidata.org/wiki/Q138883901","name":"DuoCircle LLC","url":"https://www.duocircle.com","sameAs":["https://www.wikidata.org/wiki/Q138883901","https://www.crunchbase.com/organization/duocircle-llc","https://www.linkedin.com/company/duocircle","https://github.com/duocircle"],"subOrganization":[{"@type":"Organization","@id":"https://www.wikidata.org/wiki/Q138898167","name":"DMARC Report","url":"https://dmarcreport.com"},{"@type":"Organization","@id":"https://www.wikidata.org/wiki/Q138897474","name":"AutoSPF","url":"https://autospf.com"},{"@type":"Organization","@id":"https://www.wikidata.org/wiki/Q138897912","name":"Phish Protection","url":"https://www.phishprotection.com"}]},"sameAs":["https://www.wikidata.org/wiki/Q138897474","https://www.linkedin.com/company/autospf","https://x.com/autospf01","https://www.g2.com/products/autospf/reviews"],"contactPoint":{"@type":"ContactPoint","contactType":"customer support","url":"https://autospf.com/contact-us/"},"knowsAbout":["SPF Record Flattening","Sender Policy Framework","Email Authentication","DNS Management","DMARC","DKIM"]} ``` ```json {"@context":"https://schema.org","@type":"WebSite","name":"AutoSPF","url":"https://autospf.com","description":"Automatic SPF flattening and email authentication management. Resolve SPF lookup limits, flatten SPF records, and maintain email deliverability across all your domains.","publisher":{"@type":"Organization","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. Resolve SPF lookup limits, flatten SPF records, and maintain email deliverability across all your domains.","parentOrganization":{"@type":"Organization","@id":"https://www.wikidata.org/wiki/Q138883901","name":"DuoCircle LLC","url":"https://www.duocircle.com","sameAs":["https://www.wikidata.org/wiki/Q138883901","https://www.crunchbase.com/organization/duocircle-llc","https://www.linkedin.com/company/duocircle","https://github.com/duocircle"],"subOrganization":[{"@type":"Organization","@id":"https://www.wikidata.org/wiki/Q138898167","name":"DMARC Report","url":"https://dmarcreport.com"},{"@type":"Organization","@id":"https://www.wikidata.org/wiki/Q138897474","name":"AutoSPF","url":"https://autospf.com"},{"@type":"Organization","@id":"https://www.wikidata.org/wiki/Q138897912","name":"Phish Protection","url":"https://www.phishprotection.com"}]}}} ``` ```json [{"@context":"https://schema.org","@type":"BlogPosting","headline":"How to Use SPF Lookup Results to Audit Third-Party Email Senders","description":"Use SPF lookup results to audit third-party email senders, identify unauthorized services, and improve email security and deliverability.","url":"https://autospf.com/blog/spf-lookup-results-how-to-audit-third-party-email-senders/","datePublished":"2026-08-20T00:00:00.000Z","dateModified":"2026-08-20T00:00:00.000Z","dateCreated":"2026-08-20T00:00:00.000Z","author":{"@type":"Person","@id":"https://autospf.com/authors/brad-slavin/#person","name":"Brad Slavin","url":"https://autospf.com/authors/brad-slavin/","jobTitle":"General Manager","description":"Brad Slavin is the founder and General Manager of DuoCircle, the company behind AutoSPF, DMARC Report, Phish Protection, and Mailhop. He founded DuoCircle in 2014 to solve the SPF 10-DNS-lookup problem at scale and has led the company's growth to 2,000+ customers. Brad's focus is product strategy, customer relationships, and the commercial and compliance side of email authentication (DPAs, SLAs, enterprise procurement) rather than hands-on DNS engineering.","image":"https://media.mailhop.org/autospf/images/authors/brad-slavin.jpg","knowsAbout":["Email Security Strategy","SaaS Product Management","Enterprise Compliance","Customer Success","Email Deliverability Business"],"worksFor":{"@type":"Organization","name":"AutoSPF","url":"https://autospf.com"},"sameAs":["https://www.linkedin.com/in/bradslavin"]},"publisher":{"@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. Resolve SPF lookup limits, flatten SPF records, and maintain email deliverability across all your domains.","parentOrganization":{"@type":"Organization","@id":"https://www.wikidata.org/wiki/Q138883901","name":"DuoCircle LLC","url":"https://www.duocircle.com","sameAs":["https://www.wikidata.org/wiki/Q138883901","https://www.crunchbase.com/organization/duocircle-llc","https://www.linkedin.com/company/duocircle","https://github.com/duocircle"],"subOrganization":[{"@type":"Organization","@id":"https://www.wikidata.org/wiki/Q138898167","name":"DMARC Report","url":"https://dmarcreport.com"},{"@type":"Organization","@id":"https://www.wikidata.org/wiki/Q138897474","name":"AutoSPF","url":"https://autospf.com"},{"@type":"Organization","@id":"https://www.wikidata.org/wiki/Q138897912","name":"Phish Protection","url":"https://www.phishprotection.com"}]},"sameAs":["https://www.wikidata.org/wiki/Q138897474","https://www.linkedin.com/company/autospf","https://x.com/autospf01","https://www.g2.com/products/autospf/reviews"],"contactPoint":{"@type":"ContactPoint","contactType":"customer support","url":"https://autospf.com/contact-us/"},"knowsAbout":["SPF Record Flattening","Sender Policy Framework","Email Authentication","DNS Management","DMARC","DKIM"]},"mainEntityOfPage":{"@type":"WebPage","@id":"https://autospf.com/blog/spf-lookup-results-how-to-audit-third-party-email-senders/"},"articleSection":"intermediate","keywords":"","image":{"@type":"ImageObject","url":"https://media.mailhop.org/autospf/spf-record-tester-5850-1787244026337.jpg","caption":"SPF Lookup Results"},"speakable":{"@type":"SpeakableSpecification","cssSelector":[".answer-block","h1"]}},{"@context":"https://schema.org","@type":"FAQPage","mainEntity":[{"@type":"Question","name":"How often should I re‘audit third‘party SPF records?","acceptedAnswer":{"@type":"Answer","text":"- Weekly for dynamic vendors, monthly for static; immediately before major campaigns or DMARC policy changes. AutoSPF schedules per‘vendor cadences and alerts on any mid‘cycle drift."}},{"@type":"Question","name":"Is it ever acceptable to use ptr or exists in SPF?","acceptedAnswer":{"@type":"Answer","text":"- Generally no; both introduce fragility and can be abused. Prefer explicit ip4/ip6 or scoped a/mx. AutoSPF flags ptr/exists and generates safe, explicit replacements."}},{"@type":"Question","name":"Should I add vendor IPs directly or use their include?","acceptedAnswer":{"@type":"Answer","text":"- Use the include if its tenant‘scoped and well‘maintained; otherwise pin explicit IPs to control scope and lookup count. AutoSPF simulates both paths and recommends the safer option."}},{"@type":"Question","name":"What if a vendor wont share IP ranges?","acceptedAnswer":{"@type":"Answer","text":"- Require a documented include with SLAs on change notice, ensure DKIM alignment, or isolate via a delegated subdomain. AutoSPF provides a vendor requirement template and checks compliance."}},{"@type":"Question","name":"Can I rely on SPF alone for DMARC pass?","acceptedAnswer":{"@type":"Answer","text":"- Not reliably in forwarding scenarios; ensure DKIM signing and alignment. AutoSPFs DMARC Simulator shows where SPF will fail and DKIM must carry the pass."}}]}] ``` ```json {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://autospf.com/"},{"@type":"ListItem","position":2,"name":"Blog","item":"https://autospf.com/blog/"},{"@type":"ListItem","position":3,"name":"Intermediate","item":"https://autospf.com/intermediate/"},{"@type":"ListItem","position":4,"name":"How to Use SPF Lookup Results to Audit Third-Party Email Senders","item":"https://autospf.com/blog/spf-lookup-results-how-to-audit-third-party-email-senders/"}]} ```