01 · Definition
What is spf lookup?
An SPF lookup — or SPF record check — reads the Sender Policy Framework record published as a TXT record on your domain. SPF tells receiving mail servers which IPs and hostnames are allowed to send mail using your domain in the envelope sender. When a receiver sees a message claiming to be from noreply@yourdomain.com, it does an SPF lookup on yourdomain.com and decides whether to accept, soft-fail or reject.
The tool above resolves the domain's TXT records, locates the v=spf1 entry, and displays the raw record alongside the final qualifier (-all, ~all, ?all) and a count of the direct DNS-lookup-consuming mechanisms. Read the SPF lookup guide for a full walkthrough of SPF record syntax, common errors, and how to interpret the results.
02 · Process
How it works
- 1Query the TXT records.Resolve
yourdomain.comfor TXT records and find the one starting withv=spf1. There must only be one. - 2Parse every mechanism.Split the record into its components:
ip4:,ip6:,include:,a,mx,exists:,redirect:andall. The tool counts any mechanism that triggers a further DNS query —include:,a,mx,exists:,ptr:andredirect:— toward the RFC 7208 limit of ten. - 3Count DNS lookups.RFC 7208 caps the chain at 10. Going over triggers a
permerrorand receivers will treat the message as if SPF doesn't exist — exactly the case attackers want. - 4Read the final qualifier.
-allrejects unauthorised senders.~allsoft-fails (commonly junk-foldered).?alland+alleffectively disable SPF and should never appear in production.
03 · Risk
Why it matters
SPF is one third of the modern email-authentication baseline (SPF, DKIM, DMARC). Without it, any sender can spoof your domain into the inbox. With it misconfigured — too many lookups, missing senders, an over-permissive qualifier — the protection is theatre, not real.
For regulated firms, an SPF that silently fails is a compliance issue, not just a deliverability one. Mailbox providers downgrade unauthenticated mail to spam, the customer never sees it, and the firm has no audit trail of what was actually delivered.
04 · Use cases
Common ways to use this tool
- Pre-launch audit. Before a new sending domain goes live, confirm SPF is published and within the lookup limit.
- Vendor onboarding. When you add a new ESP or transactional provider, verify their
include:string is present and the chain didn't push you over 10 lookups. - DMARC rollout. Verify SPF alignment matches your DMARC policy direction — start at
p=none, then move towardp=quarantineandp=rejectwith confidence. - Spoofing investigation. When customers report phishing claiming to come from your domain, an SPF lookup confirms whether the attacker's IPs would pass or fail.
- Mergers and migrations. Two firms combining brands need to consolidate sending infrastructure without dropping any legitimate sender on day one.
05 · Interpretation
What to check in the result
The tool returns four things — read them in this order:
- Lookup count under 10. If the count is at or above 10, SPF is failing for some receivers right now. Trim or flatten
include:chains. - Single record. If you see two records starting
v=spf1, SPF willpermerrorimmediately. Merge them. - No
+allor?all. Either qualifier accepts unauthorised senders. Move to~allwhile learning,-allin production. - Every legitimate sender represented. Marketing ESPs, transactional providers, billing systems, payroll, calendar invites — each needs its own
include:or IP. Missing senders silently lose mail.