Currently I'm storing all my outgoing mail in an mbox file, so I could also periodically scan that file, or maybe scan my exim log for the outgoing message IDs. But first, I need to determine if an incoming mail is a bounce before I can decide whether I want to see it or not...

I did test my module against the mails of yesterday and the two days before, and it finds all bounces. More I can't say :-)