[exim] Maildrop + Quota Full, no bounce message

Hello,

I am running Exim4 with virtual users from a mysql databse. Mails are delivered through courier maildrop into the maildirs. Everythign works fine except that if a mailbox goes over the quota, maildrop just fails with error code 75 and exim will defer the message trying to deliver it again. I would like to bounce the messages back instead so people who try to send mail are quickly notified that the mailbox they want to send to is full.

Exim4 mainlog when the mailbox is full:
2011-03-06 20:05:43 1PwIKa-0001OD-5j == someone@??? R=mysql_user_maildrop T=mysql_maildrop defer (0): Child process of mysql_maildrop transport returned 75 (could mean temporary error) from command: /usr/bin/maildrop

If i test maildrop directly i get this result:
# maildrop -d accountname < test.eml
maildrop: maildir over quota.

Is there a way i can stop exim4 from retrying maildrop deliveries and maybe add a custom error message to the bounce saying the mailbox is full?

Thanks