Running Mailscanner AFTER sendmail?

[Spam Account]

I have recently switched four different clients over the Mailscanner,
and we have generally
been very happy with it.  However, there is one issue that has cropped
up that is really giving me fits.

Previously, we were running sendmail only.  Email recipients would
immediately be checked against
the sendmail hashes, and invalid users will be rejected during the smtp
connection.

The problem I have here is that since installing mailscanner, I have
noticed
many unknown user messages in the maillog.  The remote spammers start
"guessing"
which accounts may be active.  The spammers will usually try 10 -
20 accounts at a time.

It's not really a problem for a user, as eventually the message reaches
sendmail and is rejected.  However I would rather not have the message
accepted at all (even temporarily) if the user does not exist.  While
the message is
rejected by sendmail, the fact that it was orginally queued from
Mailscanner has let to even more of this,
as spammers think that they have hit on a valid account and add it to
their lists.

So a solution to this would involve one of the following:

Either A) Have sendmail accept the initial message, perform the
necessary user lookups, pass to mail
scanner, and then get it back and deliver it.

or B) Make Mailscanner somehow aware of the sendmail hash so that
spammers will get "user unknown"
during the initial email send attempt.

Is there any way to do this?

Thanks.
Scott.

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