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Re: [Asrg] SICS

2004-12-21 22:55:38
Since you're an ISP, could you indicate roughly the numbers you are
talking about (per user if you like)?  [...]

I'm not bzs, and the numbers I have aren't quite the ones you ask for,
but they're harder numbers than I've usually seen cited. :-)

One of my tasks at $DAYJOB has been to deal with the crippling load
caused by spam blowback.  (Yes, crippling.  It had gotten to the point
where they were having to shut off all incoming SMTP during peak
periods just to keep the mailserver up at all.)  I wrote a small shim
layer whose job was to turn away unknown local-parts very cheaply.

The reason this is relevant is that I had it keep stats.  Thus, I know
what percentage of the RCPTs offered were rejected - ie, were totally
invalid local-parts.

At the peak of the blowback, when I first put it in place, it was
running about one in two hundred - 99.5% of the RCPTs offered were
invalid.  (These days, it's much better; it cruises along at only
something like 75% - I just now took a data sample, and while it was
too small to be really all that significant, I have no reason to think
it was unrepresentative, and it showed 93 bad and 32 good.  This
matches with my own memory of the sort of numbers I've seen when I've
looked at them in the past.)

That's just totally invalid local-parts.  Some amount of that is
doubtless non-spam (a very small amount - see below); there is also
doubtless a significant quantity of spam among the mail aimed at
existing local-parts.  I did arrange to capture some of the rejected
traffic, and when I looked, it was approximately all bounce blowback
from spam - other messages were notable by their rarity, and most of
*them* were non-bounced spam.

/~\ The ASCII                           der Mouse
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mouse(_at_)rodents(_dot_)montreal(_dot_)qc(_dot_)ca
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