[exim] Retry Mailbox is Full

In exim.conf I have this.

begin retry

*                      *           F,2h,15m; G,16h,1h,1.5; F,4d,8h

This is fine but I would like an exception on mailbox is full. I have
a number of mailboxes that are full on my server and would rather that
exim not waste resources retrying writing messages to them starting at
15 minute intervals. Is there a way to tell exim on them to only
retry every 6 hours or so?

Matt