[Mimedefang] SPF Usefulness (was Re: SNARE spam detection)
kelson at speed.net
Wed Jul 29 20:49:31 EDT 2009
> It's useful as a message REJECTION tool. It can also useful when the
> method passes, in that we have a responsible IP address to complain
> to or about.
SPF and DKIM are also useful as one component of whitelist data, because
an SPF pass means you can trust the envelope sender's domain name.
1. You want to whitelist mail that's definitely from example.com.
2. example.com publishes an SPF record.
3. If you get mail that claims to be from example.com *and*
passes SPF, you whitelist it.
4. If a message fails SPF for example.com, or passes SPF for another
domain, just let it run through the normal filter path.
This is how SpamAssassin's whitelist_from_spf and whitelist_from_dkim
methods work. (Well, mostly. It still runs through the regular
filters, just subtracts a bunch of points at the end.)
SpeedGate Communications <www.speed.net>
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