I broke something, because it *was* working. On my ISPConfig install I have two sites. One is "www.strangenoises.org", the other is "www.tantalus.org" <not really, real name obscured>. Each "site" has co-domains set up, "strangenoises.org" and "tantalus.org" respectively, plus some others. Mail addressed to firstname.lastname@example.org is turning up in my inbox (email@example.com). That mailbox is also the defined Admin and Catch-All address for the strangenoises.org domain. 'jim' is the defined admin and catch-all address for tantalus.org. There is no 'jim' user in the strangenoises.org domain. (btw, I've defined no username prefix, so "firstname.lastname@example.org" maps to actual user "jim" and so on.) I've no idea why the tantalus.org mail is coming to me. Here is what I find. When it happens, mail.log shows: Code: Sep 20 21:48:35 aziza postfix/local: 79EF43444E47: to=<email@example.com>, orig_to=<firstname.lastname@example.org>, relay=local, delay=2.9, delays=0.1/0.01/0/2.8, dsn=2.0.0, status=sent (delivered to command: /usr/bin/procmail -f-) ... which doesn't give me much clue as to why it did it. It's happening both to incoming mail from outside, and from mail sent through the same server (by me, testing). /etc/postfix/localhostnames does contain: Code: tantalus.org www.tantalus.org /etc/postfix/virtusertable does contain: Code: email@example.com jim @www.tantalus.org jim firstname.lastname@example.org jim @tantalus.org jim What's going on? More importantly, how can I fix it? I'm still hunting myself, and in a slight hurry! If I'm true to form, I'll probably post my own answer which I can't possibly find until I've posted the question. :-} P.S. It's an Ubuntu Feisty server with Perfect Setup (following the howto here) and ISPConfig 2.2.16, all recently installed. I did recently change the IMAP/POP3 server from courier-imap to dovecot (to solve problems with some users using Apple Mail.app) but I can't see how that would break *this*.