On Fri, 29 Sep 2006, Rob McEwen (PowerView Systems) wrote:
Jon Trulson said:
Hehe, that is an old spammer trick... Our secondary MX is
pretty much 100% spam.
I implemented greylisting on the secondary which reduced spam
through it by about 99% :) The secondary does not do spam
scanning, it's simply store and forward. Greylisting really
helps in these cases.
Jon, please tell me, what portion of your overall spams attempt to comes in
through this secondary MX compared to all spam that you catch which are headed
to your primary MX record.
THAT is what I most wanted to know.
Sorry, I missed that... It's hard to gauge right now as I've
been running this setup for over a year. But, before
greylisting was put into effect, I would say nearly 80% of our
spam came through the secondary MX - it seemed to be the
prefered mode of entry into our network.
Most 'dictionary' type spam entered this way as well, since
the MX did not have a list of valid users - it's only intended
as an emergency backup after all.
I highly recommend greylisting for secondary MX systems. :)
Thanks!
Rob McEwen
PowerView Systems
--
Jon Trulson
mailto:[EMAIL PROTECTED] http://radscan.com/~jon
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