[ietf-dkim] Re: ISSUE 1525 -- Restriction to posting by first Author breaks email semantics

[Charles Lindsey]

On Sat, 19 Jan 2008 16:38:32 -0000, Hector Santos <hsantos at santronics.com>  
wrote:

> After reviewing this, I think we have no choice but to lookup all the  
> co-author's domains, regardless of the presence of sender.  At best,  
> Sender can be use to change the lookup order.

Which does not give you any benefit that I can see. More useful would  
always be to lookup the Sender in SSP just as if it had been in the From  
header.
>
> Examples:
>
> #1: sender matching domain
>
>     From: p1 @ a.com, p2 @ b.com, p3 @ b.com, p1 @ c.com
>     Sender: p4 @ b.com

In that case, you have already looked up b.com in the From, so no need to  
do it again, of course.
>
> #2: sender no matching domain
>
>     From: p1 @ a.com, p2 @ b.com, p3 @ b.com, p1 @ c.com
>     Sender: p4 @ d.com

That might be where p4 at b.com was a mailing list expander. If the mailing  
list published an SSP and signed, then that would get checked (though I  
doubt mailing lists would often be specifying "strict").

If any of [abc].com was 'strict', then the message would get through iff  
the mailing list had not broken their sig(s). If they were all 'all', then  
it would get through if either their sig worked or the mailing list's sig  
worked.
>
> #3: no sender
>
>     From: p1 @ a.com, p2 @ b.com, p3 @ b.com, p1 @ c.com

No problem in that case.

-- 
Charles H. Lindsey ---------At Home, doing my own thing------------------------
Tel: +44 161 436 6131                       
   Web: http://www.cs.man.ac.uk/~chl
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