On Sun, 6 Jun 2004, Michael R. Brumm wrote:
Take a look at:
http://www.michaelbrumm.com/spf-forwarding.html
Let me know if there are any mistakes.
SES does not concern the forwarder. It is something that originators
will want to do in any case to reduce forged bounces. I suppose what
the chart is trying to say is that forwarders which implement RSR
or SUBMITTER are not contributing as much to thwarting forgery as are
forwarders which implement DBBF or SRS.
I would add a fourth(fifth) option - forwarder does nothing - for completeness:
SPF+Nothing
-----------
Modifications required:
Originator None
Forwarder None
Receiving Whitelist trusted forwarders
Disadvantages:
Receiver is at the mercy of the truster forwarders anti-spam effectiveness.
Whitelisting forwarders can require significant database work on the
receiver for large email providers - especially if the whitelisting is user
specific.
The goal is to move away from SPF+Nothing, so I would list the
options in order of increasing effort: Nothing, RSR, SRS, DBBF, SUBMITTER.
This is also the order of increasing effectiveness - except for SUBMITTER,
which looks like a loser to me.
I would like to encourage forwarders to do any of RSR, SRS, DBBF, with
the most brownie points for the most effective measure (DBBF).
--
Stuart D. Gathman <stuart(_at_)bmsi(_dot_)com>
Business Management Systems Inc. Phone: 703 591-0911 Fax: 703 591-6154
"Confutatis maledictis, flamis acribus addictis" - background song for
a Microsoft sponsored "Where do you want to go from here?" commercial.