Finally after much moaning of mails being sent to systems@php.net bouncing and volunteering to write a SRS plugin for George's ecelerity software, they have added in SRS support which means Jim and George don't bounce these messages anymore, which is a good thing (tm).
The SPF Addoption Roll which generates the graph you can see here shows a couple of interesting facts about sites that have submitted their domains which contain SPF records (dns TXT records which look something like the following:
Which basically says something like SAIX's SMTP servers on SAIX's Cape Town Belville Services LAN, UUnet's smtp.uunet.co.za and three IP's on our San Jose box can send from @ataris.co.za and in the interim allow softfail mode. We are migrating as many users over to using authenticated SMTP so that we can start flagging domains as -all and only allow relaying via specified SMTP servers on our network.
I've changed various aspects of my SPAM filtering capabilities on the mailserver to start using SPF which rejects forged emails from @freebsd.org for example at SMTP time. Also I've started requiring that the mailhubs start using SMTP callouts to verify sender email addresses. This also helps get rid of excess SPAM prior to Spam Assassin which is resource intensive from having to handle the mail. We will see how things shape up with the changes.
