Meng Weng Wong wrote:
> On Jul 12, 2007, at 9:15 AM, Marc Perkel wrote:
>
>> Need a rule written to take advantage of this trick and this could be
>> a major breakthrough in white listing.
>>
>> Here's what it needs to do:
>>
>> 1) Take the IP of the connecting host and do an RDNS lookup to get
>> the name.
>> 2) Verify that the name that was looked up resolves to the same IP
>> address.
>> 3) Look up the name in this dns list ===
>> example.com.hostdomain.junkemailfilter.com
>> 4) if it returns 127.0.0.1 - it's ham

>
> I'd like to suggest that where the domain publishes SPF, we use that;
> where it doesn't, we use your algorithm.
>
> I recently coded up a very similar approach; I posted about it on the
> SPF and Karmasphere mailing lists. Here is the original message:
>
>


SPF is rather useless. Spammers can publish SPF records.