At 11:30 PM 3/3/2005 +0100, you wrote:
David MacQuigg wrote:
> Can a typical mail transfer, with authentication at each forwarder and
> receiver, work correctly when some MTAs used SenderID, and others use
> SPF? Or will all stations have to provide both?
That depends on what you mean by "use Sender-ID" and "use SPF".
What I mean is some MTAs will SenderID protocols only, defined however
Microsoft defines them, and other MTAs will be done using only open-source
protocols, without any Microsoft licenses.
If you mean that some MTAs use "v=spf1" and "v=spf2/mfrom" records for
authentication of the MAIL FROM and some MTAs use "v=spf2/pra" records for
authentication of the PRA (effectively the headers), then it will work in
a technical sense (i.e. at least it will not break), and it will be all
the more effective the more both sets of MTAs overlap.
If you mean that some MTAs use "v=spf1" records for authentication of the
MAIL FROM and some MTAs use (the same) "v=spf1" records for authentication
of the PRA, then as far as I can see it will not work properly. But,
strictly viewed, we lack substantial amounts of empirical data to
conclusively answer the question.
If I understand this correctly, senders will need to publish both spf1 and
spf2/pra records to be sure that their policy works with MTAs that
implement only one or the other.
What about communicating the results of authentication downstream? Will
forwarders need to prepend headers for both types of authentication?
What about implementations of spam filters and other components at the
receiving end? Will each implementation have to follow different protocols
in searching the headers to determine which domain to use for blocking and
filtering?
-- Dave
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