Quoting Alastair Campbell:
> Thanks for the reply Jakob. Are you saying that it would be best to use
> the second option (quoted above), instead of the first, or as well?
I'd use only the first one.
> That second one doesn't seem to identify that it's a bounce, or am I
> misunderstanding?
Bounces usually have an empty sender address, so you can use that criteria.
> I also assume that this is the file you mean?
> acl_check_rcpt = /etc/exim4/conf.d/acl/30_exim4-config_check_rcpt
Oh, I don't know debian's Exim config scheme, but it sounds promising.
There's a exim list for Debianians, btw, see
http://www.exim.org/eximwiki/DebianExim4.