Email setup looks confused and isn't working

I've just installed Virtualmin on a clean CentOS 5 system. I've set up my first virutal domain, and its website, and FTP users, all with no problems.

Now I'm setting up email users and can't make them work. First I tried with names like domainname_username@domainname, then with just username@domainname. I have the setting to not add domain name automatically to user names unless needed for disambiguation.

Taking the simplest case (simple user name, no forwarding rules) I have created an email user debbie@tripwise.net. I send her an email and it bounces with the message: 550 : Recipient address rejected: User unknown in virtual alias table

Looking behind the scenes I find the following:
in /etc/postfix/virtual, an entry that says
debbie@tripwise.net debbie

In Webmin > Servers > Read User Mail > debbie, the page says
User Mail
This user has no messages in [~/debbie/Maildir/]

In Virtualmin > tripwise.net > Edit Mail and FTP Users > debbie, the pages shows:
Quota and home directory settings:
- Home directory quota: 50MB (28kB used)
- Home Directory: Automatic
Email settings
- Primary email address enabled: Yes
- Inbox mail file: /home/tripwise.net/users/debbie/Maildir (New mail received 29/Sep/2008 11:23)
[Note, I chose users and not homes as my mail subdirectory name]
Mail forwarding settings:
- Yes, deliver to mailbox
Virtualmin > tripwise.net > Edit Mail Aliases
No entry for debbie

So, the email was received (it's in her mailbox in tripwise.net/users) but the system also sent a bounceback, and Read User Mail takes me to some other location where it finds an empty mailbox for Debbie.

Where did I go wrong? How can I fix it?

Status: 
Closed (fixed)