Unknown user again

[Bill Anderson]

Hi,

I have been doing some digging on trying to understand how to fix my
"Unknown User" issue where Mailscanner is used as a gateway to other mail
servers.  My problem is that spam email destined to an unknown user on
another server serviced by my gateway, ends up piling up in my queues and I
end up sending an undeliverable message to innocent bystanders who are
unlucky enough to be in the forged from address.

I have seen several solutions mentioned in this list, however, none of them
quite fit my environment.  I am running Mailscanner and sendmail as a
gateway.  The gateway serves as a spam and virus filter for several diverse
/ non-integrated mail servers.  Here is what I have found as possible
solutions, but for some reason or another it doesnt quite solve my solution
in all cases.

1)  LDAP - many of the the servers don't support LDAP.  The ability to build
a comprehnsive LDAP server is outside of our scope.

2)  accessdb - can be done, but very time consuming trying to coordinate
with the other admins to get a complete list.

3)  Use something else other than sendmail - sendmail is all I have and
changing would be verrrrrry difficult.

Ok now that I have ruled out all of my options does anyone else have any
other ideas?  Here are some things I think I could use, but not sure if
Mailscanner or sendmail can do it.

1)  Is there anyway I can tell MailScanner and/or sendmail to not respond to
a 550 unknown user error?  Bascially Mailscanner tries to deliver an email
to an unknown user.  Once it gets the 550 error, it drops it.  I know the
downside of what if it was an honest mistake, the sender would not be
notified.  I would like to do this on a domain by domain basis.

2) Can I talk to multiple LDAP databases depending on what domain the
address is destined to.

3) Can the accessdb be integrated and used alongside the 2 items above?

Basically I need to do a combination of all 3 on the same server.  Any help
would be much appreciated.

Bill Anderson

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