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 [email protected] is turning up in my inbox ([email protected] (btw, I've defined no username prefix, so "[email protected] 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 protected][email protected] ... 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 protected][email protected] 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*.