On Mon, 8 Mar 2004, Ilan Aisic wrote: > Before I go and implement it in my DNS, I'd like to solicit opinions about > it from the list.
"It can't hurt but it might not help much." SPF is designed to solve a specific problem: Joe-jobbing, that is, the forgery of your domain-part in the sender addresses of spam. It specifically cannot prevent a spammer from using any domain whose DNS is under his (legitimate or otherwise) control, on mail that is sent through open relays/proxies, hijacked PCs, etc., because all the spammer would need to do is advertise in his own SPF records that those locations are allowed to send his mail.
