[Exim] How to disable bouncing

My exim has bounced some messages in past right after receiving them
from fetchmail. Hopefully, those were just mailinglist posts. I would
rather want such messages forwarded to some account at localhost,
whatever caused delivery failure. I have now errors_copy in exim.conf,
but that still sends bounce to sender and I am not sure whether it works
at all. So how can I configure exim to work "quietly", without answering
any messages?