[Greylist-users] Skipping greylisting based on SPF?

[Ken Raeburn]

Valor Romá <romalopez at gmail.com> writes:
> If my experience can help, I have been using this approach for time
> ago. First, SPF check. If SPF PASS, no other checks done, mail passes
> to mailbox. If SPF FAIL, mail is rejected. If other result, then
> greylist, DNSBL, etc. etc.
>
> In all this time I haven't detected just a single spam message than
> came from a SPF PASS check. This solution works very well for me.

If that's so, great.  But I don't trust blocklists very much, hearing
various stories of lists that "advertise" that they're shutting down
by simply indicating that all mail should be blocked, hearing stories
of sites trying to get off of a list by fixing what they're told to
and even trying to talk to the list maintainers but still staying on
the list, and working at a school that for internal political reasons
can't yet stop certain behavior that gets them listed as an open
relay, despite having people working to stop any large-scale abuses.

I've read recently on one of the IETF mailing lists (via archives, so
offhand I'm not sure if it was recent or months ago) that some
spammers are starting to use SPF records for their sites.  If those
sites are listed with blocklists, and you use blocklists, you win, but
it sounds like just SPF without a blocklist might not be good enough.

Do you have any estimate how many sites pass SPF but are blocked by
DNSBL?

Ken