Educause Security Discussion
mailing list archives
Re: Extremely High Spam Statistics
From: Jeff Kell <jeff-kell () UTC EDU>
Date: Tue, 13 Feb 2007 09:21:19 -0500
Just to add another data point, we "accept and deliver" only 5-10% of
the SMTP connections pointed at our gateway.
We don't accept SMTP other than at the gateways.
We null-route egregious sources altogether (Spamhaus DROP list) and
don't track those statistics.
We ACL-block SMTP from a few dozen other netblocks (clustered sources
created from 'top 20' spam stats from our gateway).
We rate-limit another sizeable chunk.
RBLs catch between half and 2/3rds of what's left.
The remaining gets analyzed/filtered by the gateway (virus, attachment,
bad recipient, content, etc)
About 5-10% gets through.
I think the percentages being reported are variable based on what you
actually call "spam" relative to the number of SMTP delivery attempts.