How to stop bounce-back emails?

It seems that recent update has changes something in how bounce-back emails are being created. Now we are getting blacklisted, because of some user's email account being full - our server sends out a lot of emails :

A message that you sent could not be delivered to one or more of its recipients. This is a permanent error. The following address(es) failed: ...

I remeber there was a setting in Exim configuration not to send such emails and emails ended up in queue. What has changed, why and how can we reject email delivery attempts during SMTP session, so they don't reach us at all?

Anton.

 

In fact none of these options suit us anymore. Before the change - server would not even accept such emails and would defer them - so we did not have to deal with them in any way. Now they are filling up queues on servers and generate outgoing emails with notification, that recipient's mailbox is full. Such messages contain original email, which in it's turn, contain spam message. I have set all servers to "defer deliver", but still - mail queue is growing and server sends out notifications. I want to stop them and make server act as before. Is it possible?