On Jan 5, 2008 4:39 AM, Julian Mehnle <julian(_at_)mehnle(_dot_)net> wrote:
Alessandro Vesely wrote:
I've read some posts on this list about SOFTFAIL. I agree with
most of them saying it is a debugging feature. As such, it
leaves something to be desired, doesn't it? I'd propose the
following addition:
If example.com says "~ip4:1.2.3.4", then a receiving server
should send a DSN to postmaster(_at_)example(_dot_)com saying something
like
Hey,
someone did actually manage to send a message from 1.2.3.4
Here are the relevant headers...
Nearly a breakpoint, isn't it?
Possibly a mandatory string (e.g. "SPF: SOFTFAIL") either in the
subject or in some other header may help postmasters to properly
collect their debug messages.
Besides my dislike for mandating receiver policy, I think mandating
receivers to send DSNs (delivery status notifications AKA bounces, for
those who don't know the acronym) is a particularly touchy issue.
I agree with Julian on this. Many receivers get so few legitimate DSNs that
they would rather deal with each as the situation requires. While it may
make sense to automatically send a DSN in the example above, where the
postmaster at example.com should be interested in what happens at IP 1.2.3.4,,
in the more common case of ~all, the DSN will go to a forged address.
However I do like the idea of making it more clear that the ~ qualifier is
supposed to be a testing tool, not a permanent band-aid for SPF's alleged
"forwarding problem" as many domain owners seem to think.
I just can't see how to introduce new semantics into SPFv1 (e.g. by adding
a "testing=yes" modifier and _deprecating_ the ~ qualifier), given that
there are about half a dozen stable open implementations of the "classic"
SPFv1 and probably dozens of proprietary ones hidden in commercial
software. Most of the existing implementations will probably NEVER be
changed to adopt those new semantics.
What might make sense here is a more subtle "upgrade" in the meaning of
~all, one that is "backward compatible" with existing implementations. It
could mean the same as -all for messages sent direct to the final
destination, and continue to mean ~all for forwarded messages.
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