About the SPF Checker
SPF (Sender Policy Framework) is a TXT record that lists the servers allowed to send email for your domain. A domain may publish only one SPF record, and evaluating it may trigger at most 10 DNS lookups — includes, a, mx, ptr, exists and redirect all count.
The checker expands every include, counts lookups, flags syntax errors and shows exactly which mechanism matches a given IP. If you exceed 10 lookups, remove unused services or replace includes with ip4/ip6 ranges.
What is SPF?
Sender Policy Framework is a TXT record listing every server allowed to send email for your domain. Receivers compare the sending IP with this list. A record may use at most 10 DNS lookups (include, a, mx, ptr, exists, redirect) — above that, SPF breaks for everyone.