Analyze & generate SPF
SPF errors are the most common cause of delivery problems. The SPF Toolkit analyzes your record, counts DNS lookups (limit: 10!), resolves includes and generates a clean, valid replacement record if needed – including flattening for overly long chains.
Guest mode: limited usage. Register for free for unlimited usage, history & statistics.
Register freeWhat is SPF?
SPF (Sender Policy Framework) is a DNS-based mechanism that specifies which servers are authorized to send email on behalf of a domain. Receiving mail servers check the SPF record to detect forged senders. RFC 7208 allows a maximum of 10 DNS lookups per SPF evaluation.
How it works
1. Enter domain
Enter the domain whose SPF you want to check.
2. Analyze record
Count lookups, resolve includes, find errors.
3. Create new record
If needed, we generate a clean, valid replacement.
Features in detail
DNS lookup counter
Instant warning when your record exceeds the limit of 10 lookups.
Include resolution
All includes are resolved recursively and rated individually.
SPF generator
Validated records with one click – with quick templates for Google & Microsoft 365.
SPF flattening
Overly long chains are automatically converted into flat records.
Error detection
Syntax errors, duplicate entries and invalid mechanisms instantly visible.
No account needed
Free and without registration.
Frequently asked questions
What is the DNS lookup limit for SPF?
SPF allows a maximum of 10 DNS lookups per check. Every include, a, mx or ptr counts. Exceeding the limit causes a "permerror" – your emails get rejected.
What is SPF flattening?
Flattening replaces nested includes with their direct IP networks. This lowers the lookup count – but the record needs more maintenance, as IPs must be updated manually.
How many SPF records may a domain have?
Exactly one. Multiple SPF records cause a "permerror" – the checker warns you immediately.
Does the toolkit support IPv6?
Yes – ip6 mechanisms are fully supported and validated.