Re: [PLUG] Spam Elimination

["Michael C. Toren" <mct@toren.net>]

On Fri, Jan 21, 2005 at 08:33:40PM -0500, sean finney wrote:
> it's an abuse of the smtp protocol, for starters.

I disagree; it's completely within the protocol, and a clever hack to
distinguish between fire-and-forget mailers and true store-and-forward
mail servers.

> it doubles the network and processing usage of legitimate mail servers,
> which maybe isn't a big deal for a personal mail server but for large
> installations can be a significant impact.  

While it does increase the resources required for a remote host to
send me mail, it's hard to make the argument that it doubles load.
The network overhead for example is tiny, as 4xxx temporarily failure
messages are returned after the RCPT TO, well before the DATA segment.
Additionally, only the first message for the <IP,sender,recipient>
triplet is affected -- afterwards, the triplet is whitelisted.

> also, it's only a stopgap measure against the spammers, because as
> soon as they catch on they'll just try to send the same message twice,
> and then you're working twice as hard with the same results.
[..]
> Right Now, i hear it has pretty good results, but i'd expect the
> effectiveness to wear off in a couple years.  so it goes.

My thoughts were pretty much the same when the technique was first
widely discussed about 18 months ago.  Given how effective it sill is
today, if it continues to be effective for another two years I'd say
that's a very decent run, and I'll gladly make use of it during that
time.

-mct

-- 
perl -e'$u="\4\5\6";sub H{8*($_[1]%79)+($_[0]%8)}sub G{vec$u,H(@_),1}sub S{vec
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forX8){$c=scalar grep{G@$_}[$i-1Y-1Z-1YZ-1Y+1ZY-1ZY+1Z+1Y-1Z+1YZ+1Y+1];S$iY,G(
$iY)?$c=~/[23]/?1:0:$c==3?1:0}}$u=$n;select$M,$C,$T,.2;redo}^;s/Z/],[\$i/g;s/Y
/,\$_/xg;s/X/(0..7/g;s/P/print+/g;eval' #     Michael C. Toren <mct@toren.net>
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