Pete:
In your alias file, as your last rule, put *: username
Does that really work for you? I had trouble with it because with a line like this, the alias file can never fail. Exim would qualify "username" and run it through again, it would also run any aliases generated by other rules in the file through a second time, and wind up mapping lots of addresses to "username@qualify_domian" Maybe I just ran into trouble since I have include_domain on and explicitly handle several virtual domains in my aliases file....but the *: construct was a big enough gun that I sure blew my foot off with it! -- Ward