Bob Poortinga wrote:
SPF in its current form implements a method for domain name administrators
to express policy through TXT records in the domain name space. SPF
could reasonably be extended to express policy for IP space administrators
through TXT records in the IN-ADDR.ARPA name space, e.g:
1.168.192.in-addr.arpa. IN TXT "v=spf1 -all"
This will be just one more of the many IP address based blacklists we have
now. And it has been shown that they are not very effective. It will disable
only zombie machines sending spam.
Roger