[Gllug] Configuring SPF to cope with secondary incoming mail servers

[Karanbir Singh]

Jason Clifford wrote:
> On Mon, 4 Dec 2006, Karanbir Singh wrote:
> 
>> why bother testing when most of the spam comes from domains that dont 
>> publish a spf record ?
> 
> That's rather akin to asking why anyone who want to whitelist known 
> senders. 

have you actually tried doing a cost-analysis for spf ? Whitelisting is 
a _very_ different sort of ballgame.

> SPF has the potential to indicate whether a message really did originate 
> from the domain it purports to come from. Suitably combined with other 
> metrics it can help to reduce spam and the problems of joe jobbing.

yes, i agree. In theory its nice. But for it to be of some real value, 
it needs massive traction online. Specially from ISP's and Hosting 
companies. Unfortunately they dont seem to like it ( cost and/or 
ownership issues ? ).

>>> Having no SPF record simply means the domain registrant/hostmaster either 
>>> doesn't know or care about SPF.
>> on one mail system I admin, we get between 2.4 - 2.6 Millions emails a 
>> day, enabling SPF achieves a net result that does not even translate to 
>> a complete percentage in discarded emails.[1]
> 
> Who ever said that on it's own it was a solution?
> 
> Have you measured the specific value on it's own of every sa rule you 
> implement (or equivilent)?

not every rule, but a _lot_ of them yes. We make it a point to specially 
look at all expensive ones ( cpu / network ).

- KB
-- 
Karanbir Singh : http://www.karan.org/ : 2522219 at icq
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