fc-rDNS: Note that this is particularly efficient at cutting spam, it essentially means that a spammer must control both the DNS and reverse DNS zone to pass the test, killing the bulk of zombified spam proxies living on infected home computers. #OpenSMTPD#OpenBSD
@akpoff It doesn't have to agree though with the hostname on the mail though, right? Else it would prevent companies that host the domains of others. I suppose most ISPs don't bother with the forward lookup of their customer's ip addresses.