From: Walter Dnes <waltdnes(_at_)waltdnes(_dot_)org>
Of the 34,740 spam in my 39 day rolling log that were not relay
probes, 15,025 or 43% had sender domains from among the 784 domains
listed in http://www.rhyolite.com/anti-spam/freemail.html
Do you have separate spam stats for where email claiming to be from
service X actually is from service X, versus email claiming to be from
service X actually is from service Y?
I don't have "stats". Instead I wrote a script that ground through
what were at the time 34,740 milter/DCC log files. It took from each
log file the sender domain as it was handed to the sendmail.cf
Local_check_mail rule and then canonicalized. Then it `grep`d through
the flat file that generates part of my access_DB.
...
This is less draconian than blindly rejecting based on envelope
sender. It still catches spammers, but has a lot fewer false positives.
For my particular situation, the false positive rate of my blacklist
of free provides is less than 0.05% of all mail sent my direction
and less than 0.5% of legitimate mail. Your results may vary.
Vernon Schryver vjs(_at_)rhyolite(_dot_)com
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