On 2015-09-10 04:45, Robert Mueller wrote:
Is there any evidence it's been useful in any way to help stop or identify spam?
No. But it's moderately good at helping identify when a message is from the sender it claims, and this is useful information.
I love that I can give users a one click "Allow everything from this address/domain" without giving a free pass to forged messages. And without having to guess at every outbound MX a sender uses today, and without having to maintain that list tomorrow.
SPF:PASS, valid DKIM, mail coming from the MX or a rDNS match all help identify whether a message is likely coming from an authorized sender, and if so, that can be useful information.
Similarly, if I get spam from @cotapmail.com (again), and it has SPF:PASS or valid DKIM, I known I can safely block the whole domain (whether future mail validates or not) and not have to care about losing legitimate mail, whereas it's not fair to block a sender because a spammer is forging their domain.
SPF's neutral, none, softfail and fail responses are mostly just noise. So is it useful? Yes. But does it stop spam? No.
-- Dave Warren http://www.hireahit.com/ http://ca.linkedin.com/in/davejwarren _______________________________________________ mailop mailing list mailop@mailop.org http://chilli.nosignal.org/mailman/listinfo/mailop
