spf-discuss
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Re: [spf-discuss] solving the forwarding problem

2005-09-11 15:09:42
Stuart D. Gathman wrote:

On Sat, 10 Sep 2005, Theo Schlossnagle wrote:

Forwarders, even those who don't care about SPF, do not break SPF.
The "show stopping consequences" you describe are simple a braindead
receiver, who installed/purchased a forwarding alias, but neglected
to account for it in their SPF setup.

You talk about a receiver that uses and alias and a receiver who controls an SPF record as the same person. They hardly ever are. The

No, no.  Their SPF *checking* setup.  Of course, we are not talking
about what they may or may not publish.  They are the "receiver", after
all, not the "sender".

It is the SPF *checking* setup that often gets screwed up by receivers.
There is more too it than simply running the algorithm.  It involves
the same complexity as publishing SPF, in fact.  Just as publishers have
to track down all the ways they send mail, and SPF receiver has to track down all the ways they receive mail. Once they do that, they
can arrange to check SPF *only* at their border, and safely
reject on SPF FAIL.  If they can't or won't do the home work (the usual
case), then they can't safely reject on FAIL.
Sorry you talk abou the receiver that uses the alias and a receiver who controls their inbound mail setup as the same person. They hardly ever are. One is a user and the other is a mail exchange administrator. One does not have control over what the other does.

--
Theo

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