Domain & DNS Tools

Email Security Checker

Check SPF, DMARC and DKIM for any domain. SPF lookup counts are resolved recursively so you can see exactly how many of the 10 allowed DNS lookups your configuration uses, and which includes are consuming them.

How SPF DNS lookups work
SPF (RFC 7208) limits evaluation to 10 DNS-consuming lookups. Mechanisms that count toward the limit are: include, a, mx, ptr, exists and redirect.

ip4 and ip6 mechanisms do not cause DNS lookups and are free to use.
Exceeding 10 lookups causes a PermError — receiving servers treat this as an SPF failure.
DMARC requires both SPF and DKIM to be evaluated; either alone is sufficient for a DMARC pass if alignment holds.