SPF Checker
Validate a domain's SPF record and its DNS lookup count, with issues flagged.
SPF lists the servers authorized to send mail for a domain. It allows at most 10 DNS lookups before it fails. No signup required.
How to use the SPF Checker
- Enter the domain you want to validate (for example, example.com).
- We fetch the live SPF record and count its DNS lookups.
- Review the record, the lookup count against the limit of 10, and any issues.
Frequently asked questions
SPF is a DNS TXT record that lists the servers authorized to send mail for a domain. Receiving servers use it to check whether a message came from an approved source.
SPF allows a maximum of 10 DNS lookups when it is evaluated. Exceed that and SPF returns a permerror and fails, so keeping the lookup count low is essential.
The all mechanism at the end of an SPF record sets the default. -all is a hard fail (recommended), ~all is a soft fail, and +all is unsafe because it authorizes anyone.
Monitor this automatically
DeliverSignal runs these checks daily and alerts you when something breaks.
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