[linux-elitists] AOL says goodbye to AT&T/Comcast and residential mail spools
Sun Apr 13 18:15:52 PDT 2003
On 13 Apr 2003, Nick Moffitt <firstname.lastname@example.org> wrote:
> begin Martin Pool quotation:
> > On 13 Apr 2003, Nick Moffitt <email@example.com> wrote:
> > > begin Martin Pool quotation:
> > > > Thousands of observed Korean spams, zero observed blocked
> > > > non-spams.
> > >
> > > That strikes me as a sampling problem.
> > I haven't done a statistical analysis to work out how confident we
> > can be in the sampling. Possibly there are some (or many) people
> > posting from Korea who are unfairly being blocked.
> And you would have few, if any, means for observing if there
That's true, because they're bounced by the MTA.
Most of the gray-area spam is caught by Mailman or bogofilter and
sequestered into a Mailbox for manual review. This shows that <1% of
caught mail is actually nonspam (which is forwarded to the lists), and
about 1-2% of spam makes it through.
We do rough quality control on the MTA blacklists by checking the
sender and recipient addresses. Spam has patterns which do not occur
in real mail: for example, obviously bogus envelope addresses, the
same IP quickly sending many unrelated envelope addresses, sending to
unrelated destination addresses, sending to destination addresses
which should never receive mail, sending to ancient and unused
addresses, etc etc.
I suppose we could change to a different system which would also
sequester mail blocked by source address. (Last time I checked,
SpamAssassin was too resource-intensive to be used.)
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