~/tools/mail/spf-generator
SPF Generator
Build an SPF TXT record from authorized senders, with a DNS lookup-limit check.
Authorize the domain's own mail servers (its MX hosts) to send too.
Authorize the domain's own A/AAAA addresses.
One address or CIDR range per line.
One address or CIDR range per line.
A third party's own SPF record, one domain per line — each costs a DNS lookup.
-all rejects unauthorized senders outright; ~all only flags them.