I’ve been working on and off with creating an SPF module for SFE. I’ve always intended it to be one of the major parts of the spam analysing process, but the specification is more complicated then I care for at times, so I’ve been going pretty slow.
One of the things I have been doing is caching the SPF records for 24 hours so that I don’t have to do the DNS look-up every single time. I’ve written a few reports that are pretty interesting about SPF and how well it is being adopted by Internet users.
At this point only 22% of domains that I have seen send email through SFE have SPF records.
You can find the real-time reports at http://spf.spamfreeemail.com These reports are cached for 1 hour and they SPF records are updated every 24 hours and they do reflect the real data for SpamFreeEmail.com.
I’ll create new reports as I find the time. If you have any ideas on reports to create feel free to leave them in the comments.