(1) Perhaps people are not familiar with how GreetPause works.
It was introduced in sendmail 8.13.x
Upon the socket connection, ordinarily sendmail opens the SMTP
transaction with a Greeting - if the sending agent respects the protocol
it will wait for this greeting before sending anything down the socket.
Spam mail is often 'slammed' - it waits for nothing and simply stuffs
everything down the pipe.
So, GreetPause simply pauses a short time (1-5 seconds typically)
before sending the SMTP greeting - normal respectful sending agents wait
for the greeting. Slammers dont - so the presence of premature data
signals slammer spam. Sendmail will then close the connection and not
accept any of the data .. lock stock and spam.
Since much spam is sent exactly this way, it is quite effective
(together with other tools). This is true of Pc bots as well as the
large farms - they dont want to delay - they want their spam out the
door in bulk.
(2) graylisting.
I sense some defensiveness or aggressiveness by some on this issue,
tho i know not why.
I know it can work well - and I'm fine for those that are happy
with it and tune it well.
I don't use it - primarily for the additional lags it imposes on
mail and coz without it my spam is very low.
Most of these delays can certainly be tuned out and .. more I think
about it I have most of the tools to do just that!! .. heh maybe I shud
tune it and try it .. my spam is a trickle (1-5 a week) without it ..
except for the ones that vger kindly forwards to me :-)
(3) There is no single cure for spam - there are lots of good tools
and using a combination (I use spamassasin too as I said in my very
first response) is the best approach.
(4) DKIM is underutilized too ... and as alan said, SPF is poopy!
This thread is great - its informative and its good to see real
practitioners discussing the issues ..
gene/
--
users mailing list
users@xxxxxxxxxxxxxxxxxxxxxxx
To unsubscribe or change subscription options:
https://admin.fedoraproject.org/mailman/listinfo/users
Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines
