Everyone, I realized (doh!) that I neglected to attach
the patch that I described below.  So here it is 3 weeks 
later.

This is the patch to perform verify sender routine.

Feedback is welcome :)

ari



On Tue, Mar 23, 2004 at 06:56:56PM -0500, Ari Jort wrote:
 
> I've implemented a verify_sender routine as inspired by 
> the postfix address verification, noted below.  Patch
> is attached.
> 
> I added a subroutine in EvalTests.pm called verify_sender()
> that will verify a given address with an appropriate mx.
> It needs a mechanism to get the envelope-from for this
> to be effective.  This implementation relies on the header
> Return-Path: which postfix adds to messages.
> 
> This routine can be invoked from a local.cf like this:
> 
> header UNVERIFIED_ADDRESS eval:verify_sender()
> 
> 
> The postfix address verification is described here:                           
>                        
>                                                                               
>                        
> http://www.porcupine.org/postfix-mirror/newdoc/ADDRESS_VERIFICATION_README.html
>                       
>                                                                               
>                        
> I'd like to use this technique, but would rather assign
> a score with SA, rather than make a reject/accept decision
> in the mta.
> 
> This is a naive implementation in many ways.
> 
> 1) It assumes the envelope-from is retreivable from the 
> Return-Path: header which is true in postfix-land.  I'm not
> sure about elsewhere.
> 
> 2) There's still a bunch of debugging code in here.  I thought
> I'd leave it in in this patch, in case it helps anyone else
> get it working.
> 
> 3) It relies on 2 extra perl modules: Net::DNS and Net::SMTP
> which might be better outside the spamd process space.  Maybe
> a sender verification daemon?
> 
> 4) It only checks with the highest priority mx record for a given
> domain and does not move on to lower priority records.  Simplicity
> is the reason here.
> 
> 
> I'd love some feedback or reports on whether anyone else
> can get this working.

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