[exim] Retries for satelite relay

Hi,

I have a server setup with Exim 4, which acts as a greylisting
relay in front of the "real" mail system.

This works well (extremely well in fact), but I have a little
problem with the mail queue growing to 10000+ frozen messages,
frozen because the "real" mail system either rejects the recipient
or because it refuses to act as a relay (the greylisting relay
accepts everything and forwards it to the real mail system).

So, is it possible to have the greylisting relay discard messages
that are rejected with a 550 relay not permitted / unknown user
immediately, or after lets say 2 tries?

Thanks,

Morten