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Re: CBV systems - was Re: SMTP Extensions - proper reply code for disabled commands

2004-01-15 14:52:15

CBV - Callback Verifier.

It began in the Modem Dialup BBS days when the telephone caller id (CID) was
made possible from the phone company and compliant modems.   The CID is
provided between the first and second RING.

When the user dialed up,  CBV software performed various "call backs" to
validate the user in some form or fashion.   The simplest validation was to
ask for the phone number and compare it against the CID.  More advance
validations actually performed a call back to the CID.  For our Wildcat!
software, there are hundreds of modem based CBV 3rd party software.

When the internet came around, some of the authors continued the concept to
periodically validate email addresses usually by sending an email to the
user when they connected to the BBS.

In terms of SMTP,  when the sender issues the MAIL FROM: return path,   a
CBV will take this return path and perform a similar SMTP based callback as
if it was going to send a reply.  But it just go as far as the RCPT TO:
state to see if the return path is bad.  If bad, then we have a 100% true
negative.  If the remote says it is GOOD,  well,  you accept it and move on.

When I first started my anti-spam efforts, I was seeing that some people
(unfamiliar with older systems, including idiotic patent lawyers trying to
lay claim to a call back system) were calling this a "Challenge Response"
system.   I would not call it that.  It is not a challenge in the
traditional sense.  It is much closer to a traditional dynamic caller id CBV
concept.  For the legal eagles, this "business method" has been in place
since the day the CID was made possible with the phone companies.
Conceptually,  the SMTP protocol  client connection IP is equivalent.
However, to perform the callback it has to be based on the IP of the email
domain host.

Hector Santos, Santronics Software, Inc.

----- Original Message ----- 
From: "Richard O. Hammer" <ROHammer(_at_)earthlink(_dot_)net>
To: "IETF-SMTP" <ietf-smtp(_at_)imc(_dot_)org>
Sent: Thursday, January 15, 2004 4:03 PM
Subject: Re: CBV systems - was Re: SMTP Extensions - proper reply code for
disabled commands

I am trying to follow this thread, but do not know what CBV stands
for.  Could someone enlighten me?  Thank you.

Rich Hammer

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