A library to evaluate SPF policy records

Complete, usable library to check whether a received email passes a published SPF (Sender Policy Framework) policy.

It implements all of the SPF checker protocol as described in RFC 7208, including macros and PTR checks, and passes 100% of the openspf and pyspf test suites.

A DNS stub resolver using miekg/dns is included, but can be replaced by anything that implements the spf.Resolver interface.

As well as providing an implementation of the SPF check_host() function it also provides hooks to instrument the checking process. The included example client uses these to show how an SPF record is evaluated.

import "github.com/wttw/spf"

ip := net.ParseIP("8.8.8.8")
result, _ := spf.Check(context.Background(), ip, "[email protected]", "aol.com")
fmt.Println(result)