undeliverable message handling - over quota

I get several undeliverable messages a day from users on our list (I'm the
admin) that are overquota. It doesn't really do me any good to see these
messages.. how to you , if you can, send them to null or whatever?

Occasionally when someone moves away, I get "undeliverable: unknown user"
error messages and I would like to keep getting those error msgs. So
basically I just want to filter out the over quota ones. Possible?

many thanks, Jim