Logwatch report issue

It's been a long struggle to get the logwatch reports to be mailed to myself, with much more file editing than I remember having to do on the FC4 boxes. Now the report emails go out to root and get delivered into my own mail - so far so good. The problem is that my filter fails, because the messages say that they come from logwatch(a)localhost.localdomain instead of hostname.domain.tld. /usr/share/logwatch/default.conf/logwatch.conf appears to be the same as on this FC4 box, where the messages are correctly identified. Postfix.sendmail is doing its part, delivering correctly, so I don't think it's there. Which other file should I be checking? Anne