From: Jan van Hoek (NL) 

>> (...) i want, when somebody intern or from outside
>> send him an e-mail to auto respond with Standard Error Msg:
>> That user doesnt exists/That e-Mail dont exists.

Though not exactly what you want, we've solved this problem via our
virus/content scanner in our DMZ, which cooperates with the firewall via
CVP (content vector protocol) and can instruct the firewall to drop inbound
messages. That's what we did for e.g. the INFO mailbox, that was spammed to
death (OK, I know that we have to have an INFO mailbox, as per some RFC.
Sue me, if you want). Instead of letting the firewall drop the inbound SMTP
for this user, you can send back a specific message, virtually anything you
want and is provided by your virus/content scanner.

Above mechanism does not work, however, for internal e-mail that is
processed by Exchange alone, and does not involve the firewall and content
scanner combo. An alternative can be to let this be done by some anti-virus
companion (if you have any) that runs next to Exchange. In our case that is
NAI Groupshield, that has similar functions as the content scanner in the
DMZ has. We use Groupshield as a second opinion, and I know that it also
inspects internal mail.

Not knowing anything on the rest of your perimeter defense lines, the above
reaches the limit of what I can propose for you. Is there any reason that
you want to hide this person's mailbox (knowing the background, may help us
to suggest some alternative).
--
-- Jan van Hoek (NL)
-- Fri 2 Jul 2004 16:34 CET

--- BBBS/NT v4.01 Flag-5