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Date:      Mon, 23 Mar 1998 11:22:34 +0200 (SAT)
From:      Graham Wheeler <gram@cdsec.com>
To:        hackers@FreeBSD.ORG
Subject:   Re: freebsd-hackers-digest V4 #75
Message-ID:  <199803230922.LAA11291@cdsec.com>

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> Stupid for your situation, Terry, not for mine. Blocking all hotmail is
> not fine for us, because some of our customers are using hotmail. So we're
> to punish everyone that uses an email address who's domain has ever been
> forged? We don't have metered usage, and aren't near capacity either, so
> it's not a serious cost. For the record, I still go through every spam we
> receive and contact the ISP of the injection point if it's apparent, and
> notify anyone that looks like they got used as an unwitting relay, and my
> time is probably a much more significant cost than the bandwith of 3% of
> our email, which even that is a drop in the bucket compared to how much
> surfing gets done during lunch around here.

We block all hotmail and a number of other sites. More than 50% of the
rejected spam we receive is (purportedly) from hotmail. When people complain
that they can't use hotmail accounts we get them to move to others that are
less abused, like juno.com.

As you say, checking and trying to have action taken against each spam 
message is costly. That's why blocking such sites can be doubly effective -
not only do you not waste the bandwidth but you save yourself having
to check the spam that gets thrown out. Even when we block a site, we 
let it get as far as the MAIL FROM: and RCPT TO: lines; I get a daily report
of all the remote hosts, the purported sender, and the purported receiver;
this is enough to quickly check whether any legitimate mail got inadvertantly
blocked (which is very rare; about one message per month). It's much easier
to deal with that one than with the many spams.

regards
Graham
-- 
Dr Graham Wheeler                          E-mail: gram@cdsec.com
Citadel Data Security                      Phone:  +27(21)23-6065/6/7
Internet/Intranet Network Specialists      Mobile: +27(83)-253-9864
Firewalls/Virtual Private Networks         Fax:    +27(21)24-3656
Data Security Products                     WWW:    http://www.cdsec.com/




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