Deleting Bounces for unkown users

[Hendrik den Hartog]

Hello, we'd appreciate some expert help advice.

At our site [a school] we have a high turnover of students.
We get several emails for students who have left, 99.99%
[probably 100%] of which are list/spam/etc.

Using Kevin Spicer's methods as per the FAQ, we stop the
mail for unknown users at the Firewall, this saves them
being processed by Mailscanner and forwarded to the
internal server and thats great! (Thanks Kevin).

However, the only option for 'ldap_routing' feature
is BOUNCE, several sites seem to refuse returned mails,
so these messages end up sitting in mqueue going through
the 'motions'

Is there any way to have these messages DELETED instead
of bounced? or, are there any [safe] scripts around which
can grep/delete email for 'unknown users' from mqueue?

Any help/advice appreciated

Cheers!
Hendrik