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  Re: SPF and Greylisting? (mod 5/31)
by Mouring ( ( on Fri Jul 17 20:38:00 2009 (GMT)
Google uses SPF to advertise their outgoing mail servers. Can't spamd check if the resend is from a machine authorised by the domain owner and treat it as a valid resend if both the original and the reply are from SPF-approved domains? You'd probably want to ignore ?all records when doing this, but anyone who publishes accurate SPF records could then resend from any of their mail servers.

Before being forced to move to postini a few years back due to an email address being bounce-bombed (even at that postini helped half my load, but I still had to apply heavy handed procmail filters). I had a simple script that polled SPF entries for a list of "problem children with SPF records" and built a whitelist file for them every night. It worked well.

A simple extension to support this more natively would be interesting. I'm not sure I would accept every SPF record presnted to me, but allowing it to be used as a white/black list entry may be useful.
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