[Exim] Dealing with a broken destination server.

Hi all,

I have a situation in which a client is using a custom anti-spam
solution. Unfortunately they have not bothered to read RFC 2821, and
after the message is sent, their servers returns a 451 (temporary
error), which causes Exim to continue to try sending the message later.
The client has made it clear that this behavior will not be changing
("because everyone else does it" amongst other explainations). I have
two questions:

1. Is it possible to force Exim, in the instance of this host, to view
a 451 error as permanent and drop the message after sending?

2. Can I force mail for a single destination host to be queued until I
manually initiate a queue runner for that mail?

Thanks,

-- Stephen.