All of these are valid points to argue, but without addressing a fundemental
point (not described in most) RMX proposals from my understanding. That is,
DNS can also be used to validate an IP reverse map so that not only the domain
is checked but also the IP. In that case, IMHO, one could argue that an
additional check for IP origination or relay of delivery would mitigate the
concerns.
I could definitely be wrong but that always sticks out to me as a
mis-understanding of that type of proposed solution/strategy. I don't think
the forwarder of mail has to be penalized for forwarding if they are properly
registered in the forwarding path (open-relays are another matter in my
opinion) and are no longer used in the historical context (helping a
brother/sister system out).
On Saturday, May 03, 2003 5:51 PM, Daniel Feenberg
[SMTP:feenberg(_at_)nber(_dot_)org]
wrote:
An Economist's Take on RMX-style Proposals to Curtail SPAM
In my understanding, the most cogent reason presented for why RMX
protocols are undesirable is that forwarded mail retains the original
envelope MAIL FROM, while coming from an arbitrary source.
The source is arbitrary only when an open-relay is involved. Thus the
forwarding path of a message should have determinacy. I don't think eMail
traverses random paths. And if it does it shouldn't. Maybe that is what needs
to be fixed.
8<...>8
Therefore I believe that the eventual equilibrium is that many domains may
register allowed SMTP sources for their outgoing mail, and some will
reject incoming mail which does not match one of the registered domains,
but that essentially no sites will reject mail from non-participating
domains and spammers will not use registered domains in MAIL FROM:
addresses. Net improvement: little or none.
I would reject mail from non-registered servers/domains if they were a spam
source. I don't think that messaging system managers ignore those types of
situations and just allow all mail. In fact I think we are moving toward a
point where 'management' will demand the sysop to block all mail from, per se,
unknown sources.
Of course we are not at the final equilibrium yet, but the more relays are
closed, the harder it is to maintain one. This could be called a "virtuous
circle" because once started it becomes stronger and stonger on its own
accord.
I agree.
-e
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