Our message systems, in the past, in order to do filtering and routing (we
have over 60 domains) accepted all email to those domains and did address
checking later.
To answer the second question from Kurt... If I am understanding your
question correctly, No. There is no way to really tell because we do not
keep historical data for 550's for the purpose of analysis and my systems,
before we started address checking, didn't know about 550's. So there is
nothing to compare. My anti-spam scripts care more about how many 550's I
get, not which ones I am getting. However, I was able to remove over 8000 ip
addresses and ranges from our untrusted domains list due to these addresses
not trying to attach to us anymore. I can correlate most of the removals to
the fact that we started address checking, but I do not have empirical data
to "prove" that.
Regards,
Damon Sauer
-----Original Message-----
From: Jon Kyme [mailto:jrk(_at_)merseymail(_dot_)com]
Sent: Tuesday, August 19, 2003 9:16 AM
To: ASRG
Subject: Re: RE: [Asrg] 2.a.1 Analysis of Actual Spam Data -
Experimental Desi gn
At 4:31 PM -0500 2003/08/18, Sauer, Damon wrote:
It is not C-R.
Sorry, my mistake. I misunderstood.
You give me a RCPT TO: the RCPT TO: is checked against my
address database. If it is good I say OK. If it is bad I say 550 No
such
user.
Okay, now I'm really confused. I thought that most mail systems
did this -- if you try to send mail to an account that doesn't exist,
they respond with an error and refuse to accept the message. Thus,
the mail volume goes down.
Is there something additional that has been done here?
Indeed, many systems do not. A customer on a network that I'm familiar with
called the operations team to ask them if they could fiddle with their
firewall (in fact that firewall is managed by someone else that they hired
- which I guess they'd forgotten) to block port 25 for a particular IP
range.
The demand of generating bounces to a spam run (to no doubt forged senders)
had crippled their (exchange) server. When asked why they weren't just
rejecting unknown recipients they said that Mgmt wanted to see
"wrong email addresses". How we laughed.
And then of course there's Yahoo and many others.
--
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